I agree that we need lag to be less than 5ms with no xruns for serious musicians. It makes a difference. 

I was chatting in #opensourcemusicians about the rt patch issue and someone threw this out there: http://www.funtoo.org/Kernel/configs/realtime

I'm smart enough to get what they're doing, but not smart enough to know if this is what we're already doing in Fedora or how it'll affect other security concerns. Also the settings listed for /etc/security/limits.conf is setting you up for a bad time. 

They said they could get less than 1ms with no xruns (except at application startup) which sounds promising. Certainly if we're shooting for less than 5 ms instead of less than 1ms.