Well since no one posted I can tell you what I know. I swapped from a t150/d20 to a t5/d300. The dana 300 is a better transfer case IMO. The main thing I like is the ratio is 2.62:1 vs. the dana 20's 2.0:1.
As far as the tranny I have heard good things. I know they are stronger than my t5 for sure.