I did the G1 to K2 jump about 3 years ago. Overall, it was very much worth it. K2 is really where its at, I'm a little surprised that K1 is still working, to be honest :)
With the backups, you're really talking about running KDB or KBU (formerly BUDR) modules, as opposed to K2 core functionality itself, so the question is really more along the lines of 'is KDB or KBU any good?". KDB = storagecraft shadowprotect, KBU = Acronis. KBU has had assorted issues with off-site backups over the years (Used to use it, no longer do). I have not used KDB but I understand it to be more expensive.
Check both out and make a decision accordingly... www.kaseya.com/.../backup.aspx and www.kaseya.com/.../data-backup.aspx
Frankly, KBU basically works, but the offsite stuff can be flaky. Its been patched and mucked around with over the years, it generally works but occasionally chucks a wobbly for a variety of reasons, and wants to do a full re-copy - which is the point of pain for most users and probably what you're been reading about.