besides being twice the size and perhaps the weight?
and less magnification.

besides the BAC...
greater FOV?

huh?

The TA11 has a longer eye relief and larger exit pupil.  It also has a smaller FOV.

Actually, BAC can be used with any scope; it is just easier to do with illuminated reticles. the trijicon scopes marked "BAC" have reticles that are always illuminated.

The TA11 also has: longer eye relief, larger exit pupil, 1/4" clicks, different reticle options

However, if you find the size and weight problematic, the TA31 offers both BAC and the different reticle options in the same size package as the TA01.

pbr, do you know what the BAC is, or what it does? I have the feeling like if you did, you might not wonder. The BAC is a HUGE advantage. If you dont like the size of the TA11, and you like the size of the TAO1, look at the TA31. It is functionally very near the same optic as the TA11, but it is the size of the TA01 series.