A lot of people have an art background BTW, including this guy (and engineering too).
Let's forget the whole percentage thing - I think it's preposterous. I'm also not one to forgive poor quality because of price. When something is bad, it's just bad, there's no excuse.
We agree that everyone has to step up their game and it would be ideal and an enormous win for the consumer if everything displayed well together. I'm hopeful, but that's about as far as it goes. Both companies have shown that there can be issues displaying even their own products together, let alone those of another producer. What you've mentioned as a possible gentleman's agreement is surely spelled out in a contract and I'm sure it's binding. These guys aren't operating multi-million dollar distribution and licensing deals based on handshakes.
I accept that you prefer the HT Bespin Luke to SS's Hoth Luke, but I don't think there's any question about which one looks more like Mark Hamill from ESB, nor which one looks more photo-realistic. Maybe Sideshow's contracted factory won't pull it off in the end, who knows? But hand it to Trevor Grove for having produced hands down the best Hamill likeness ever seen in 1/6 scale.