> Is there a big difference between Fire, Fusion and Steel for TNE and

> for T4? I haven't really found many reviews for the both of them, safe

> for some that say that the TNE version is way too complex and the

>T4 version has issues. I know that both of them have copious errata.

> Or should I just go for some GURPS books instead?

I found TNEs version much easier to understand but the primary difference would be which version of the rules they derive values for. So you should get the version for the rules you are using. For CT that is High Guard and Striker. For MT it's the Referee's Manual.