In a covering one's tolerance sense, I feel that 2mg of buprenorphine is equal to the tolerance one would get from using 20-30mg of oxy per day for a year.
I've read in dosage converters that .3mg of IM buprenorphine (buprenex) = 10mg of IM morphine in pain relief.
Too much bupe is too much bupe!!
In my opinion taking more suboxone than one needs is NOT pleasant (more itching, more constipation, more sleepiness, massive tolerance to overcome!), so if you're getting more than you need and you have willpower, stockpile for a rainy day (or somebody else's rainy day). If you don't have the willpower to taper if you've got more sitting around, talk to your doc about it!
Beware, once you've been on bupe for a year, tapering your dose is NOT as easy as you might imagine (although its definately easier than tapering oxy or morphine or methadone).