i was an avid s1(v2) user, until 2 things happened:
1) the s1v3 gui seemed so cluttered, and ill-defined, i just couldn't imagine sitting in front of that for hours every day...
2) the last project i did in S1 ended up getting moved from the end of the album to the beginning...so...had to transpose keys (major/minor were involved). after having to do that manually for 70 or so tracks of midi because S1 wasn't "key aware", i bought DP (then cubase because of a sweetheart deal), and haven't gone back.
That said, i don't dislike S1. I just am gunshy of using it for midi arrangements like that (DP is my go-to for that sort of thing, and i like cubase for the simpler stuff).