Xplane users get all the Betas, Steam users get like every second beta.

Otherwise the software is exactly the same, with the exact same performance. They just can't resist the hordes of casual gamers who only comes through exposure on Steam (sorry for the serious simmers on Steam out there, but most Steam users are computer rookies and casual simmers, this is probably a reason why they don't get the beta versions - Beta's are meant for beta testers, who are willing to make proper bug reports, and not just complain that their sim is crashing, or the framerate is slow) The demo is free but times out after ten minutes. For me it was never a question who'd I rather support, and if I'd Laminar, I would only publish directly. Download the X-Plane 10 flight simulator, if you dont already have it.

There are plenty of airports you can download for free. There are plenty of airports built into X-Plane 11 that, while generic and dont necessarily match the actual airports, provide a very good environment. Because this 50% is about how much Steam pockets usually. X-Plane 11 comes with quite a few aircraft that are nicely detailed and perform well. The question is if you're rather give about 50% of your money to a multi-million dollar company (Steam) who does nothing apart from hosting the files, or you rather support a small, dedicated team of developers who ACTUALLY wrote the software and making it better day by day.

Buy x plane 11