A lot of it depends on what range of rods you want to cover. If you only have a 5wt, either one would hold the right line. If you have a 3 or 4wt, the go with the II and you can buy spools to cover those lines.
I'm of the opinion that rarely do you need a larger line/backing capacity for a trout rod. For salt and for other species, sure. But for trout? When was the last time you got spooled on a trout? So it comes down to balance. Which one balances your rod best. That you have to check out at the shop.
That all being said, I had the BLA II, and traded it in for a reel that is sexy as hell, silky smooth, and is in the same price range......The Lamson Guru. Blows my BLA out of the water.
My .02. (may be all it's worth)