I think the OP has gotten quite a few responses to think about besides the fact that this seems to have turned into a bash IOR thread.
Personally, I think the offerings from Leupold are overpriced.
For less than MK6 money, you can get into a March 3-24.
There are several Bushnells in your price bracket that you should consider.
I like my IOR (3-18x42), I like the reticle for tactical and hunting work, not so much for bench rest tiny group shooting.
IOR improved their product, I have been running a gen 4 for a considerable amount of time (about 3 years) and it has never given me a problem.
That does not discount Frank's experience, he has seen many fail at the school and during comps. However, those were not gen 4 scopes. They were earlier models and they DID have a record of problems. That is NO LONGER the case. It is quite amusing, if one company puts out a product that requires fixes, which they address, it is because they are a stand up company. Yet if another company does the same thing, they are treated quite differently.
OP,
Also, consider the Steiner, the SWFA 5-25 and Nightforce.
They make scopes that are within your budget and they all would work quite well