I run the base-bommer fuel in my 01' m750. I'm not sure if the reason is limited to the carb'd bikes. But there is talk of higher octaine fules fouling plugs and such. I was having that problem a while back, but it was PROBABLY due to other things wrong with the bike. I changed to the lame fuel fo ra quick fix, and I have not gone back. I haven't noticed any ill effects of running 87 yet.
Do a search on the forum for this, you should find lots of info about it.
I wish I could remember who made the post, but there was a pretty good explanation of why you only need to run 87 by somebody on the DML email list about 1 1/2 years ago. Anyway, since reading that, I've run 87 exclusively, track days and all, an my bike runs fine and I actually get a little bit better mileage.
If you search this board for "octane" you'll get the big low down. Long story short, unless you have high comps, cams, altered timing, or a problem you can run 87 just fine. Using 91 will actually promote carbon buildup.
I used it for most of the time (once I saw the light) I owned my 33k mile 900 and never had a problem.