Krell HTS-1 or Audio Video Standard?

I am thinking about buying a used Krell HTS-1 to partner my KSA-250 and home theater system. DVD/CD source is a Pioneer Elite DV-38A, with two Pioneer Elite M-91 power amps, B&W Nautilus 801 front, 805 rear and HTM-1 center. Current pre-amp is a Pioneer Elite C-72 and a Pioneer Elite SP-99D processor (Yes, I like Pioneer Elite. The SP-99D looks great and sounds awful!). My question is fourfold:

1. What problems can I expect with a used HTS-1, operational and maintenance?

2. What are the benefits of the Krell Audio Video Standard over the HTS-1?

3. Is there a significant sonic/video/operational benefit of using the HTS-2 or HTS 7:1 over the HTS-1 (I am not interested in 7:1 surround)?

4. What software or hardware fixes (if any) are available for the HTS-1? Is there one for the famous 2 second switching delay problem?

Audio quality, especially stereo, is of paramount importance to me, video quality is secondary. Your views on any or all the above questions would be much appreciated. Thank you for your help.

Regards,

Marcus