From what I can tell the 80TXV is the latest and the 56TXI originally the most expensive. You won't be able to get them repaired unless you have a nearby hobbyist and it's something simple like a parts exchange, but all these are likely to be and stay in good order for a long time. Pioneer receivers sound good and are reliable but at some point they really began gimping the EQ; also not sure many of these will have separate speaker crossover points.
You could go through manuals.lib to compare their specs, focusing on DACs, transformers, etc. If it turns out you do require newer feature sets I'd recommend a current brand new Sony with Atmos 7.2 at about the same cost. Otherwise there's also canuckaudiomart.com for more choices.