Re: Aimpoint PRO or T-1?
It's really the cost vs size (and a few other things). Both should serve you very well.
The PRO is obviously cheaper, has a larger tube, flip caps, and only comes in 2 MOA. It has shorter battery life. All for $400 or less.
The T-1 has a longer battery life, smaller tube, lighter weight and comes in 2 0r 4 moa. It comes with rubber lens covers or there is one mount option that allows the use of flip caps. There is also a product that will be coming to market relatively soon that is a cover with integrated flipcap-like covers. Generally goes for $550-$650, depending on mount.
I started with a T-1 for the weight savings, but recently picked up a PRO to check out. If I could do it again, I probably would have saved longer and just got a CompM4s for the even longer battery life and AA battery.
Some people have a strong preference for the larger tube of the PRO, I haven't really noticed much difference.