As far as I know the render speed wont go down that much if you fix a more frequently looping texture and uses mipmaping (using multitexturing). If you get problems with it try posting on some threads about using the shaders and see if there is something you are doing wrong.
And as you can see in games like Unreal Tournament 2003, detailmapping is not heavy at all. You just need to use it in the right way.

Any way, it might bee that you cant fix those problems for various of reasons, then... have you considered to make the bots less detailed to more match the graphics of the environment? A more united graphical style is important for a game if you ask me, more important than a higher resolution and highly technical graphic.

Anyway ^^, you game seems to come closer to a finished product :], I will be back later and hope to play a eventual demo ^^, I wish you good luck with further development and hope that it comes together as you wants it to :]