I say this in every thread about Pass amp comparisons, but it's the truth and bears repeating.
You should just call Pass directly. They're great. They can't help you with weight concerns, but can answer any questions you might have about what model will sound best given your speaker, pre-amp, and music preferences. They will not try to sell you the most expensive option, and don't really care if you're planning on buying new or used. I ignored their advice once because the internet convinced me otherwise... they were right. Reno will also be a good source, but Mark will also try to sell you a product. Pass is happy to simply opine.