My new 10-30 arrived friday and I got a chance to test it yesterday. Seems fine, charge rate and voltages to the car seem pretty similar, although I only added 30 miles of range. I use my 10-30 a lot and the old one never gave a lick of trouble.
Well, one lick of trouble. The only receptacle suitable for making an extension cord or adapter that I was able to find cost $80 from mcmaster-carr and is gigantic. I bought one, but it irritates me and I needed several 24/30 amp adapters (*). So I use L6-30 (much smaller, and $8 from amazon) and just have the one adapter. I hope they'll sell me an L6-30 adapter for my UMC so I can do away with my kludge.
-Snortybartfast
(*)10-30 extension, 14-30, L14-30, TT-30, 6-30, 14-50 30 amp downcoverter. I also have an L6-30 extension, which is a bunch smaller than a 14-50 extension, and a hack that connects an 14-50p to an L6-30r and 5-20r so I could trickle-charge my ICE battery from the same plug as I charge my tesla.