The main problem in tremulous’ tyrants (since 1.1) is that humans could not aim anything in front of them besides their allies (Just as a small exemple (Some players had it way worst back then. ): I stopped counting after my 2372nd death from being shot by a lucifer cannon, a rifle , grenades or even blasters.) I have to agree with Sayori that making healing cost evo’s is a little overkill.
What tremulous really needs (In my opinion.) is some balancing (it could also be nice to have scale-able values so it auto-adjusts depending on how many players are in-game playing. This way, the match would be even no matter what happens. What will make the difference is the players skills, which is lacking a little bit for a lot of players. (It’s not bad, not at all, we all have our forces in different areas, but some players are just better than others mostly because they have put a lot more time into understanding the game and getting better at it.)
Anyway, I don’t really think making healing useless or a pain to use will fix anything. In fact I’m pretty sure it will create even more problems.
Sure tremulous needs new content, the game’s never had anything new for a little over a decade. (Until 1.3 happened, of course.) But good content comes after the game being well balanced and made the best possible.