Yeah, Reasonably reguarly. It is (was?) indeed a dump in the past. Yes, there would be thermals generated there, but i've never had any problems with holding down kites. Also while thermals are generated at ground level, they have very little effect on anything untill about 50-60 feet up. ( I fly RC sailplanes, just so you know) My personal hate about murrarie? Its pretty bumpy. On the ol' PL at about 40k's it starts chattering like it's gonna fall apart. The bumps also limit speed a bit in a buggy, i've never had a problem on a board tho.
Sluggo flys there a bit, so he could probably give another perspective on the place.