I've got the opportunity to pick up an unused SB66c at a great price.
I currently ride a 575 and am thinking this would be a great upgrade and I can use most of my current parts on the new frame.
Two main concerns are:
1) wheels and tyre availability - not a new issue as my 575 is 26" but more acutely aware of it if I tie myself again to 26" 2) warranty etc on the frame. It's new and unused but is 3 years old and technically obsolete...
I'm tied into 26" for life. Just purchased a secondhand SB66c and I couldn't be happier. Came from an Ibis Mojo HD and the SB66 just darts forward with the rear shock completely open. Climbs incredibly well, It's a super nimble bike so you can place it wherever you want but it can handle the thunder too. I wouldn't hesitate. (unless you've already made a decision) either way ride well!