I used the SS1 when I started, but have since switched to the necklaced backup style. I had it coupled with the T2 second stage as my primary.
After doing drills, and having to actually share air a couple times in bad situations, I found I dislike having to fool with an inflator that I was breathing off of. It's performance as a regulator was flawless, it functioned as an inflator flawlessly, but for me personally when combining the two functions is a must I did not like it one bit.
If you do chose to go the SS1 route, be sure to drill and practice air share drills where you have to breath off the SS1 AND control bouyancy and your buddy and such with it at the same time.
I found I ran out of hands...But that's the beauty of diving. Different things work for different people. Just be sure you know and practice what you might have to do in a situation with it before you HAVE to get out of a situation with it.
Other than that...enjoy and safe diving!