As big as a Tremulous fan I am, I have to say he has a point.
I showed it to a friend once, and he couldn't believe how fast paced the game is.
But that's not really my beef with it, the game relies heavily on melee for the aliens,
and being so fast paced this makes latency a really big issue at times.
Often times the game just feels unfair because you have no idea what just happened,
usually has to do with the interplay of latency and lag correction.
I'm not sure if slowing down the game is the right thing for Tremulous though.
The speed is what sets it apart from other games like Natural Selection, which just feels like a slug in comparison. Trem is highly skill based, that has it's upsides and downsides. It certainly keeps the game challenging even for top tier players, I never feel like I mastered a class. The downside is the near vertical learning curve, Trem just isn't newb friendly. I think putting in a practice/tutorial mode would help a lot in that regard though.
When I talk about speeds, I'm mainly talking about dretch speed and human sprint in close combat, I feel those 2 are somewhat problematic. If I were to make a tremulous derivative (that's not tremulous) I might consider ditching the dretch and make the basilisk the starting alien (minus the grab).