I agree that Steam for Mac is still not as stable as the Windows edition (derp) but if the game you own is supported on the Mac then consider it fine. Steam for Mac isn't so unstable that support games don't work. It should be okay.
I grew up on Windows computers, used Mac at school and owned a few Macs, then owned a few PC laptops. So my entire history of computing has been a constant cross-weave of OSX and Windows and I have no particular bias towards either anymore. I use both daily. This has also allowed me to learn a heap about cross compatibility, so I'll stick around in this topic and help in any way I can. Feel free to PM me as well.