I've not had any bot problems with my dedicated servers (For clan practices), or my local machine, CPU usage in general does increase when you being a server (either lan server, or internet server), bots have to decide where to go, what to do, evaluate possible combat scenarios, 'Listen' for footsteps and gunshots etc..
If there is (for example) and intense firefight going off somewhere on the other side of the map, the CPU usage will be higher, (Calculating shot vectors etc), even though you can't see it, it's still happening. But i've never really had a problem with it.
The SDK was recently updated with a bot 'Template' file, which would allow you to create bots in other HL mods.. maybe you should look into this as well as the plugin SDK, and make a HL2
M plugin which includes bots. -- Just an idea
