My Pieps DSP (with older firmware) indicates distances down to ~0.2m - it stops outputting direction information at about 2m, requiring a switch to grid/bisection search. I'm thoroughly convinced that probing's a good idea. 2 cubic meters (>216 cubic feet) of snow is a lot of snow to search, especially if it's rock hard. That said, if I got an 0.1-0.4m reading, there's a pretty good chance that I'd skip the probe, and dig down a foot.
As a physicist, I'm convinced that well-implemented 3-antenna receivers are the way to go.
