How important do people think it is to find a processor that can set the actual sub distance for each sub rather than going with the average or closest sub difference? Is this a meaningful issue when considering a processor? On the Anthem thread, Bob P. has often stated that it is not a meaningful issue and can be worked around through sub phase and volume adjustments.

For just phase/volume I would agree that it is not important. It is particularly not important if you are colocating the subwoofers.

However, if you have a processor that has EQ capabilities, than individually EQing subs that are not colocated is a big plus. For instance the top denon receiver and their processor both have multiple subwoofer outputs, which are individually Audyssey corrected, and this is a big advantage. Now obviously, I have no idea what your budget is, so I don't know if that's feasible, but...