It is true that using Factory is probably best only if you understand that it MIGHT NOT work at some point!
Most of us get round that by having another desktop installed alongside. Myself I have kde3 Stable and kde4 Factory. I only really use kde4.
Personally I find kde4.3 very stable. I had held back for a long time with adding the kde4 network manager, but just switched to it tonight. It works just fine. There had been some issues with it for some.
I’m fortunate that my laptop hardware actually works better in Linux than it ever did in Vista.