To plug in or not to plug in?

Alright guys. I am having tons of fun with my new Wordpress and buddypress test sites but, I seem to be amounting a lot of plug ins in the process. I mean, am I greedy in wanting them all?

Can you have to many plug ins?

I guess I am looking for advice on what others do or don't do when it comes to using multiple plug ins.

I am also testing a MU site which I am not even sure I need. I have some plugins networked and others not and some on one site only, etc.. At some point it seems as though I could easily have plugged in to much and it all stops working. Or, is that something which won't happen because all the plug ins get updated properly?

Thanks for your help.