I'm one of the people that asked Andrew for a demo of MPro 4, he gave the same reason, i.e. could not support it, or provide information on correct installation. I respect that point of view, but disagree completely, because:
1) If your product requires support to set it up and install, then it's too hard. We're not talking about complicated server/enterprise stuff, we're talking about the most common consumer level type of software you can buy. But Andrew is right, I did need a bit of help setting it up.
2) I could not get a demo of MPro4, so I bought a copy anyway, on a chance it would meet my needs. As it turned out it did not meet my needs as it can only handle one IMAP account at a time, and without buying another R-Comp product, it won't work with the POP3 service provided by GMail. This meant R-Comp got a sale they would not have got had they provided a demo, whether this is a good thing or not depends on whether you are R-Comp or a customer.
3) Yes, MPro4 is about the same price as a PS3 game, I own a PS3, and I've played a few demos of games on it, they are freely downloadable. Not all games have demos of course, but it's becoming much more popular.
All that said, once I did buy a copy, Andrew bent over backwards to provide very good email support, unfortunately the problems mentioned in my second point meant that I can't really use it though.