I did a similar comparison with the 150B and the Aries G1 (search my name to read if you like). Sonically they are pretty close, IMO, and I kept my Aries simply due to the Rose not being $3k better and it also has a ton of features that I'll never use.
So, in short, my choice between your two options would be the Altair if you like simplicity or if you're looking for a lot of bells n whistles the 150b, sonically they're very close.