anyway, back to threading...once I put my UV filter on, it stays on for good...if I get a new lens with the same thread size, it is cheap to buy a new filter...
This is true. 
I do the same thing, actually. The reason I'm concerned about threading is that there are circumstances where you'll want to use, say, a circular polarizer, GND, or some other type of filter while shooting a relatively wide angle, and stacking the filters will likely get you more vignetting. So there are some situations in which you'll want to remove the UV filter.
But yeah, normally my filters stay on the lenses, and every lens I have has a UV filter on it (B+W, in this case)...

