Myerslake2005I have read your post with a lot of interest...
I like shooting the Powebelt's because I don't need a hammer to seat the bullet.
There are a lot of people using PowerBelts and they are working just fine for them - In this day there really is no reason to need to use a hammer to load and seat a bullet. There are enough different sabot/bullet combinations out there that do load easily - I, and a lot of us, find no reason to even use a short starter - thumb pressure to start the combination down the barrel and ram rod pressure from there.
45 vs 50 - that is a particularly easy question for me. The 50 offers so many advatages and varieties I would vote 50 easy - here in Idaho the 45 would not be legal anyway.
The variety of projectiles is immense if your state allows sabots. Barnes is coming out with a new bullet that has a really high BC and can be shot very succesfully across long distances. SST/Shockwaves offer a large variet of long shooting high BC bullets. I myself do not use these bullets because of expsense and probably will not experiment with them. (although I must admit I still use Noslers partitions for elk hunting. I am currently running some experiments on the new Speer Gold Dots... the 45 cal. 300 grain HP has a published BC of .233. Sighted in at 134 yard that gives me a drop of 9.5 in 200 and still well over a 1000 lbs of energy when it gets there....
Good luck in your search...