When - or rather if - it becomes bloatware (isn't everything nowadays) is the time to switch. I recently had meetings with the xMedia team at Microsoft (ex iView and MS folk) and they're mostly Mac nuts, so I wouldn't worry too much. MS are realistic and know they need to pander to the Mac market if they are to be a bigger player in the graphics area.
You could also look at programs like Lightroom and Aperture. These are more geared towards volume raw processing, and each has underpowered DAM. For example, if you want to manage non-photographic assets as part of your photo projects (eg a wedding shooter might have sound and video clips) then you'll need a DAM anyway.
I'd forget the Filemaker or mySQL idea unless you want to spend vast amounts of time to a custom solution. I tried it using SQL Server and you can certainly do it, but you'll need a whole range of skills (database SQL, programming) and you'd hit specific issues like working out how to extract image thumbnails and previews, EXIF, IPTC and XMP metadata etc etc. I can handle most of those, but it was eating far too much time and off the shelf solutions are far better.
You should see what xMedia version 2 is like, and assess whether it's worth the upgrade - ie take a cold and rational view, not through Mac-blinded eyes.