Don't judge linux by your experience with the Pi, GM. Besides the realtime issue, which isn't really an issue once you accept its a multitasking OS (although putting GPIO on it lends itself to needing realtime), Linux on the Pi and Linux on half decent hardware are two entirely unrelated animals. I use it full time, although my distro of choice is Ubuntu, Debian is close enough so the differences on the Pi aren't great. The Pi sucks because of the severe compromises made to get the price down in my opinion. You're right, it is stone soup. The choice of power supply is the root of a lot of the problems. Charging a smart phone battery is a whole different animal to running a desktop computer, factor in the polyfuses (needed to stop it overloading said PSU and wiring) and the poor USB/ethernet implementation and the whole thing becomes a pain. Its lack of grunt is sometimes a problem but I'll leave that bit alone.
I have now a rock solid Pi, (attacking said polyfuses with a soldering iron and feeding it power via the GPIO pins got rid of many of the problems I was having) , but I still can't get it to play nicely with any of my webcams (all of which are plug and play on my PC and Ubuntu) and using workarounds for talking to an Arduino is a pain. I've just ordered a 'works out of the box' webcam as a last ditch attempt to get it to do what I want, we'll see on that front.
I'd take Linux over OSX anyday but I haven't really used a Mac in earnest since Tiger.