MoFi or Harbeth (used)

Sitting off axis is an issue.  I’d go with an omni polar speaker like Ohm if I was forced to sit off axis. 

I have no experience with the MoFi speakers, but based simply on their price point and what I've seen/heard from other MoFi electronics (the UltraDeck and MasterPhono), I think their speakers would be hard pressed to outdo the Harbeths, but that's purely conjecture.  I've been impressed by the MOFI gear I've heard to date, but it seems to be priced above it's performance level.

I picked up a pair of 30th Anniversary Compact 7's a few months ago, just to compare to the other Harbeths I've owned (Super HL5 Plus 40th anniversary and P3ESR SE).  They really wowed me, as well as some of my audiophile friends, and I kept them for months, seriously considering keeping them over my KEF Reference 1 speakers.  At the end of the day, the KEFs are better, but I liked the Compact 7s over the Super HL5 Plus as well as a pair of Stirling LS 3/6 that I had.  They are great speakers.

Toeing them in could help or perhaps your preamp has balance controls.  

My concern with Mofi, as is the case with all Andrew Jones speakers, is that after the initial intro dealers just start discounting them like crazy which has a detrimental affect on resale value. Harbeth is a known quantity and if you buy used can you always sell them at little or no loss.

on paper, the MoFi is a much better value. However I heard them and I was not impressed (which could be irrelevant, could have been the room, the setup, break-in, etc.)

Harbeth is about impressive midrange - again, anecdotally - the good news is, if you are set on these two, you only have to listen to two speakers which is doable/feasible, don't listen to a bunch of nerds, listen to the speakers :)