I'll opine on this some more...
The disclaimer is I have ONLY used a Giraud, so I can't give any insight to the other machines.
I bought a Giraud because of 3 key reasons:
1. I already had his trimmer and really like it. It's a well designed, well thought out device that does the job it's designed to do.
2. The resale of Giraud stuff is high, so cost of ownership is low when you decide to sell.
3. It's the only unit on the market that has a "hopper" or "reservoir", so that it will run autonomously.
I've not found setting it up to be difficult at all. There are only a couple of adjustments on it...
1. There is a single screw that secure the rotary feeder plates to the driveshaft. There are two feeder plates, and then spacer plates to hold them apart. You can stack a different amount of spacer plates to account for different length brass. There are 3 different sets of feeder plates; 1 set to cover ~223ish cases, 1 set to cover ~308ish cases, and 1 set to cover the magnums. So far I've only annealed 243/260/708/308 cases and 284win cases. I use the same feeder plates and the same spacing for all, so I've not had to mess with the feeder plates or spacers at all, except for the initial setup. Maybe I got lucky, but I eyeballed it and said "that looks good" and it's worked great from the beginning.
2. There are 2 screws that you you use to adjust the torch position. You can tighten these enough the torch stays put, while leaving them loose enough you can adjust it with your hand as needed. I've found for the 308 and 284 cases, the distance from the torch to the carriage doesn't need to be changed. The angle of the torch does need to be adjusted however, because of the different shoulder location of these two cases. An eyeball alignment is more than adequate, and takes 10 seconds or less. I adjust the distance of the torch so that point of the blue portion of the flame will intersect the longitudinal centerline of the cartridge case.
3. There are 2 case carriages; a narrow one and a wide one. I've been using the wide one for both 308 and 284 cases.
4. Gas valve. I've almost found this to NOT be an adjustment at all. When I first started using and tinkering with the machine, I played with the balance of flame and carriage speed a lot, but I've found that isn't needed. You open up the gasvalve until you have an aggressive flame. You'll find as you open the throttle (so to speak) at a certain point the length of the hot blue portion of the flame doesn't get much longer, only the sound of the flame changes. I turn up the gas valve for about the max blue flame length.
5. Carriage speed. I turn off the lights and let my eyes get used to the darkness for a couple of minutes. I adjust the carriage speed so the casemouth is starting to turn a dull red just before it drops. You can also adjust this by watching for the "orange fringes" of flame that start to come off the case.
I will say that when I first started using the machine, I had trouble getting the flame strength/carriage speed balance correct. The "power" of the flame would change over the course of 5-10 minutes simply on account of the fact the amount of fuel (and therefore the vapor pressure) consumed from the bottle. I found I was constantly messing with the flame/speed adjustments trying to keep it balanced and correct.
Once I learned to just run the flame hard and focus on the carriage speed adjustment, this issue went away. The combination of the smallish fuel bottle and gas regulator makes it just about impossible to maintain an even, consistent flame - IF you are trying to maintain a nice easy flame. If you crank it up, it stays consistent and nice.
To switch from 308 to 284 cases takes me less than a minute. As I indicated before, the angle of the torch has to be adjusted. Without no flame, I lay a case on the carriage, look down on it from above and adjust the torch angle by hand until it looks right. Then I light the torch, turn the machine on, feed it a case and watch for the dull red. I adjust the carriage speed accordingly. It usually only takes me 2 or 3 cases to get it just right. Then I start stacking cases into the feeder.