I recently got some small t. pachanoi specimens, they are looking good. 2 sets of plants both with 4 small cacti clumped together, sizes ranging from 2-6cm. Was wondering if its better to try separating them before repotting, as I dont want to tear roots .. the roots seem quite tightly meshed.

Any advice much appreciated, thx

you could try if they are too meshed and young though and you tear they might get too injured and not recover,but wash all tho soil off so you only see the roots and untangle if you can then repot.

I would separate them if they are separate cacti... if they are grown together, I wouldn't separate them.