last month at the 15k service the dealer suggested Bel-Ray 80-140 gear lube in the primary, so I had it put in and yes it is a lot better than the HD Formula + I have used for last two changes and I liked the formula+ a lot better than the syn3 I put in at the 1k service.
Is the BelRay the best? each one of us have to decide that..
I will say it made a big enough difference, that as of now I will be staying with it.

 

I run the oil in the engine but use Bel ray for the trans and no wine or clank and I can find neutral. I use Motor Factory® Primary Case Lube in the primary. because Amsoil has gone up so much I just switched to Mobil 1 for vtwin and it works as good. I have 30,000 miles in about 1.5 years and it runs great and no debris in the oil changes.
http://www.belray.com/consumer/product.fsp?pid=13637
http://www.customchrome.com/dcm/cc/view.asp?mfoil.html