Hello,
I purchased a SP6 a few days ago. The SP6 replaces a (Casio) PX5S I sold last week. I play keys in a blues band in Lexington, KY. I also play about once a month in a worship band in Lexington. I play blues band gigs with a Nord stage 2 73 and a Korg Grandstage 88. The SP6 will be my band rehearsal keyboard because of its light weight and its front panel transpose button (the guitarist tunes to Eflat) which was one reason I sold the PX5S. I have owned many Kurzweil instruments including: K2000, K2500, K2600R, and PC2. The PC2 ended badly (many keybed problems in about 8 years use) and it took the SP6 to get me to buy a Kurzweil again. My initial impressions of the SP6 is favorable; i like the variety of APs, EPs and B3s compared to the PX5S.
I consider to do the same. Still I use a Sp4/7 and a pc3/61 from Kurzweil and a Nord5d/73. I also played the sp6 in a shop and I know, that it will be right for making music in my cover-band. But I am not sure, that the sounds are as good making music solo. Please help me! 
I've only had a few times where I've played the sp6 and just "solo jammed" AP and EP programs. My impression is that there is a nice variety of pianos and I really warmed up to one or two in the time I played. The piano program will have to fit the song - it seemed like each piano had a focused use in musical style. You may find that there's not an all-around piano voice - that can be used anywhere - but that's just the way it is.
Thank you very much! And: Yes, I know. Most of the time I use 4 or 5 different piano-voices (e.g. Studio Grand, Pro Piano, Blues Piano 74 + Upright Piano as a Layer, Blues Piano 74 and the wonderul DAVE WEISER Gig-Piano). It is the same using my Nord5d/73 - no universal Piano-Voice. 2 weeks ago I got an offer for a used FORTE88. Perhaps I will buy this one. It is heavy but great!
Merry Christmas and a Happy New Year!
Thomas
