I'm doing five T-trak modules of various configurations.
I've drilled through the 'holes' underneath Unitrack with a .035 drill in a pin vise to expose them on the top. I put the track on the plywood subroadbed, and drill once again through the top down into the subroadbed, then tap in a standard track nail using a nail set, snug but not deformed. The drilling positions it exactly where you want it and eliminates nail bending over or shifting. It's still pretty easy to pull out the nails with flush cutters if you have to, but you won't see any movement or shifting for sure.
I evolved this primarily because I didn't want to be blackmailed on the custom mounting screws.
Once I've assembled and tested the modules, and am SURE I've got everything where I want it, I'm pulling the nails, putting a line of contact cement around the base, glueing it down once and for all, and putting in the nails only on the end pieces for strength.
I also paint and ballast Unitrack.
To be perfectly honest, the only thing I love about it is the edge joint connectors- I do all other trackage in Peco C55 on cork.