I'm doing almost the same thing. My Dometic NDR1292 went out a few weeks ago and ammonia was visible on the coils. I also got a new cooling unit from RV Cooling Unit Warehouse, but after doing some research, and talking with the guy who is going to install it, I went with the Amish built unit. They make them brand new and apparently use much better quality materials than what Dometic used. The guy who is going to install it thinks he can get it done in 3 hours and will charge me $300. I paid $1200 total for the cooling unit. I had gone to an RV facility and they gave me an estimate of $2850 for the exact same repair.
I considered the residential fridge option too but to replace the fridge you have to take out a window and get enough people to be able to lift them in and out through the window. Not to mention I'd have to modify the cabinet and change the wiring because the current 110 volt outlet for the fridge isn't powered through the inverter. So it would have probably cost more to go to the residential fridge.