An Aimpoint magnifier is a very good tool, as it provides the shooter with better observation capability and makes it easier to achieve a more consistent aiming point.
I prefer to have a twist off mount, so that I can put it on and take it on based off my needs in any given situation. I have used it with a Comp M4, not a T-1, so cannot comment on whether the increase in dot size is an issue or not.
A low power variable scope is a very good tool as well, but I don't think it is the best solution for everyone. I used a S&B Short Dot for a while, and really liked it, but for 90% of what I did in the mil, an Aimpoint and 3x was sufficient.
Magnification is Alpha Omega on the Battlefield, either through weapon mounted equipment, or hand held. I prefer a combination of the two; Aimpoint and magnifier in addition to 8x30R Steiner military binoculars with reticle is what I carried.
I also do not see the weight argument. A Micro T-1 with a 3x weighs in at 405 grams including mounting hardware, a Comp M4 and 3x weighs 635 grams. I don't know how these numbers stack up against low power variable scopes that are out now, but my Short Dot is a lot heavier.
