My $0.02 worth,
You should decide if you want standard decoding of 5.1 sources to 5.1 output and 6.1 sources to 6.1 output, as well as listening to 2.0 sources in 2.0 output, versus having the option to perform surround processing to listen to any source in "quality" 7.1 output.
The former is a multi-channel pre-amp with "standard" decoding of DD, DTS, etc. The latter is a surround processor and Logic 7 in the Lexicon is a an example.
The Krell web page says the HTS 7.1 has DPLII, but not DPLIIx, so it cannot use a DPL approach to derive 7.1 output from 2.0 input. Krell talks about music surround enhancement modes, but I don't know anything about those.
The Krell does not have THX Ultra II, or equivalent, so it does not appear to be able to derive 7.1 output from a 5.1 source. Based on this, I would classify the HTS 7.1 more as a multi-channel pre-amp than a surround processor.
For me personally, I found 7.1, when implemented with a good algorithm like Logic 7, far superior to 5.1/2.0. You may have different preferences. I recommend listening to the Lexicon in a properly set up 7.1 system.