Hi, Roger:
I can't speak to the Krell, but I own the Bryston SP-1 and think it is excellent piece of equipment. The new SP1.7 is simply an upgraded SP-1, with analog inputs for DVD-A / SACD, support for 6-channel and 7-channel surround, and 96 kHz upsampling (this last item is the chief reason I would personally consider upgrading to the 1.7). For more info about how Bryston feels about having to manufacture the 1.7, rather than continue the SP-1, I suggest you read their current newsletter at this Web address:
http://www.bryston.ca/newsletters/64_files/vol6is4.html
If you are interested in a more extended dialogue about what I think of the SP-1, please feel free to drop me a personal E-mail, or call me at 206-772-1909.
Best regards,
Scott C-