I agree with a lot of what Jerry stated. I'm a firm believer in oil coolers and 2,500 mile engine oil & filter service intervals. I've had very good results using H-D 20W50 conventional engine oil in my Harleys, but I do use Redline synthetic 20W50 in my Buell due to the higher engine temperatures. Since I don't put a lot of miles on my Buell, the additional expense of using synthetic oil in it isn't a big deal. If I had engine heat issues as some are reporting, I would use Redline synthetic 20W50 or even 20W60 in warmer environments.
As Jerry stated the primary isn't that critical, so H-D Formula+ will do. It has the same service interval as Syn3, and is a little cheaper.
I ran Formula+ in the transmission once after it replaced H-D's Semi-Synthetic transmission lubricant just to see what it was like. It was okay, but I've since switched to Redline Heavy Shockproof Gear Oil, and will definitely be staying with that. Zippers sells it and it is recommended by Baker Drivetrain. 'NUFF SAID!
One advantage to running a different oil in the transmission than in the primary is should your bike develope a leak, it will be easier to determine the source.