I would have thought that there is a very large overlap between people who like WWII and WWI air combat. It is not that different. Much less overlap would be between people who like modern jet-age combat vs. propeller driven, slug shooting fights. The first is all about a million buttons, complicated systems and countermeasures, the latter is all about ACM - WWI, WWII, all the same.
I would like WWI for a change of atmosphere, but I can't see how the gameplay would be any different from what can be done in WWII era. I hate modern "fly level and work the radar" modern air combat.