at the moment I'd say that there's no reason why not to experiment on 35mm Tri-X. It's exactly what i have been doing the last week. I have 2 threads on this subject going at the moment. There are at least two contributors who have supplied invaluable help and links to relevant info. You can also see the results that I have got so far.

Caveat emptor(s). I have not yet applied my 35mm Tri-X test methods to real Super 8 Tri-X. Tri-X 35m does not have a clear base which may skew the perceptual results. So far, I have had no success with adding sodium thiosulphate to my 1st developer – it has only weakened the overall density of the image, even at 0.5 gm in 330ml developer. Still, I will work on the last factor a little more before I move onto a Super 8mm film.