1. Tikka actions, as far as I know, are based off of a military design that was subjected to harsher environments than most any Remington 700 was.
2. The only reason I don't use a Tikka action every single time myself is because... well, I don't know why? Shit... why don't I? What is wrong with me?
3. Okay maybe another "downside" is the recoil lug is a piece of metal that slots into the stock/chassis instead of being attached to/integrated into the action. But that doesn't seem to affect anything of note, certainly not in a rifle capable of going 1,200 yards, as I've seen Tikkas do in competition.