Couple things here I'd like to address
True to a point, but may be more a matter of lazy fundamentals, even with a "forgiving" parallax you still need to make parallax adjustments if you want to be truly parallax free at your target. Also, diopter plays a role here, if you're shooting at 1000 yards (or whatever distance) and no matter what you do with the parallax dial you still get wobble I'd highly recommend fine tuning your diopter - I've had this happen to me on a couple scopes and minute changes in diopter cleaned it right up.
Depending on the scope 100% in focus doesn't always mean 100% parallax free, again, diopter may play a role here so always good to verify.
I'm not sure that "many" are fine with good enough, especially at this level of the game; however, I understand your point with regard to "good enough" vs. "precise". This is likely where the F Class/benchrest shooters have an edge (and need that edge because that is the level of their competition), most of them could care less about FFP but precise parallax control is very important when they're trying to shoot a 2 inch group at 1000 yards. Now that being said, I know many F Class shooters prefer to use much higher magnifications than do PRS shooters and claim that mirage isn't the issue that it is for many who shoot dynamic long range sports, and these same F Class shooters also prefer the "less forgiving DOF" so they can focus on a narrow band of mirage (heat waves) to judge wind at various distances before their target - in this regard less forgiving is actually a benefit for many in this field, but guess what, at higher magnifications DOF and parallax are going to be a lot less forgiving than at lower magnifications or I should restate that to say the "appearance" of DOF and parallax are less forgiving (that's the way magnification works, you are magnifying everything through the optic). So is it possible that something like the TT 7-35 might actually benefit both worlds - for the PRS shooter who stays around 15x or less the DOF and parallax (or appearance thereof) are going to be more forgiving but crank up that magnification to >25x and DOF and parallax are going to be more finicky which may be just what those shooters want...
A forgiving eyebox is always a benefit, I can't think of any situation where a forgiving eyebox would be a detriment. Maybe the above situation of using higher magnification in order to get narrow DOF and require more precise parallax adjustment is the solution. Unfortunately the drive for shorter and larger magnification ranges in scopes has created some unique designs, but the finicky eyebox in some of these optics is a real beast to bring under control, that being said I do not think this new TT 7-35, even though it is shorter than it's 5-25 counterpart, falls into this class, my brief experience with it showed it being forgiving in the eyebox arena.
I appreciate your point of view expressed above and I wanted to give an alternate view from my vantage point as a long time F-class competitor. I have dabbled in PRS, but at my age, it's not something for which I am suited. After reading you post, let's just stipulate that you have never shot F-Class and you are trying to fit it through your PRS experience filter.
In F-Class, shooters want the most magnification possible. We'll get to mirage in a bit, but let's deal with max mag for now. The reason people want to have the highest magnification possible is to be able to surgically place the reticle on the target. The precision of the shots have gotten to a ridiculous level in F-Open and right behind it, F-TR is experiencing the same. When the winners are decided by the number of Xs, this means the shooters want to get able to place their 15 or 20 shots in a 5-inch diameter circle at 1000 yards. To accomplish this, you need a fine reticle and large magnification, the reverse of what an FFP scope can deliver. This is why high-mag SFP riflescopes rule in F-Class.
Of course, you remember that the size of the exit pupil is a function of the diameter of the objective divided by the magnification. So, let's take my Majesta (8-80X56) scope as an example. When I'm shooting at 80X, the exit pupil is 0.7mm. I am here to tell you that if I am not perfectly behind the rifle, I see nothing in the riflescope. When I do get a sight picture, it's because I am positioned properly behind the rifle. There is no parallax to be experienced in those conditions. Also, F-Class shooters, the good ones, have an excellent gun handling regimen. They are positioned behind the rifle properly, and they repeat the position for every shot. They also perform a proper follow through. If you go to a match and observe the top shooters, you will notice the economy of movement in position.
If they do stop shooting during a string and then restart, they will take the time to get back into that proper position, because the eyebox is NOT forgiving, and that's a plus.
I like the way you dismissed mirage by stating the F-Class shooters claim "that mirage isn't the issue..." Mirage IS an issue but not all riflescopes handle mirage the same way. There are riflescopes that do a better job in mirage than others, and that's important. All good riflescopes do a great job when the conditions are nice, but when the mirage starts roaming, the IQ degrades; it's the rate of degradation that differentiate riflescopes. When the aiming black looks like a crazed amoeba on crack in your riflescope, you have to dial down the magnification. But if the aiming black is still round and the rings are distinct, you can stay at that magnification and shoot surgically. It doesn't mean the IQ is superb, but it's usable. The scopes that do better or put another way, don't get as bad as others, also show the mirage better to the eye; they detect it better and earlier. This is an advantage to the shooter because they can take what they observe and factor it into their hold. As a matter of course, I may play with the focus ring a little bit in periods of heavy mirage, but I don't do that for parallax adjustment. I use the focus ring for its intended purpose, focus the image.
I completely understand the desire for forgiving eyeboxes in PRS competition. There's a time factor involved, with movement, and difference distances in the same string. F-Class is much more static but requires a higher level of precision. One discipline is not better than the other, they are simply different.
I like to use the term "dancing target". Either way the shimmer of the heat waves causes distortion of the target.
