Output of FX Buss

I am using Cubase 5 and I’m wondering about FX buss outputs. When I route a track via the sends to an FX Buss, i.e. guitar tracks to a reverb on an FX track, where do I output the FX track? To the main out or to a group buss, i.e. the guitars group?
If I route to the main out then I can route several instruments to it, but if I want to, let’s say, mute the guitars they will still be heard from the reverb FX buss.
If I route to the instrument group buss then I need a different FX (reverb, delay, etc.) for each instrument, but when I mute the group I mute it all, i.e. I don’t hear the reverb, etc. still coming through.
Any thoughts on this would be greatly appreciated.