I'm playing my Mark VI 135xxx with an old Precision Crafted (Phil Barone's original brand) mouthpiece with a Vandoren #3.
I mostly play tenor but started on alto and still play it quite a bit.
I'm a big advocate of playing stuff in all keys.
Here's a video of me playing the verse to Stardust in 7 different keys.
I think it really helps me to understand the song. It also improves my improv by making me really internalize the essence of the song which makes me think more melodically so...