Given that BRNAV is now pretty much mandatory for all Eurocontrol enroute stuff, and that it is all but impossible (if not actually completely impossible) to comply without an IFR GPS, then it's a necessity, not a bonus.
I agree with Stevelup. Although it is
possible to manage without en-route BRNAV in Controlled Airspace if you have to, it is now expected that you will have it, and the only practical en-route BRNAV for GA is GPS.
MJ
