Anyone have experience with one of these?

  Marey RV LPG Tankless water heater

 See ebay item# 330110332099

I've never heard of that brand of tankless water heaters.

In general tankless water heaters are lousy for homes but acceptable for RV's, cabins etc.

The main reason being the FLow Restrictors most require. You have to slow the water flow down in order for it to heat up as it passes through the heater.  People in their homes want to FEEL the water pressure blasting out of their shower head, not dribbling out.

In a RV, Water conservation is the key, so most owners will accept very low pressure as an acceptable substitute for no having to drain a tank after they get done to prevent freezing, and since most only carry  a limited abmount of water to begin with.

The Ebay item says it for a house, a similar item says its for an RV.  I would suggest you purchase that one in place of the whole house unit. It's probably more compact to fit inside a RV.

These units are really cheap in comparison to the units I see people trying to use in homes. The Bosch, Rinnai and other whole house units retail for $1000 per unit. So I'd be skeptical of something claiming to the same work for $150.

 - Slightly

We have a SEISCO electric water heater in our house for four years now, and it works great except for opening the big spigot to out jacuzzi tub all the way. Have to keep it at about half open. Otherwise can run showers in master bath room and both guest's baths at the same time and never run out of hot H2O.

At first we had a great deal of trouble with the micro-switches failing, but they replaced all of them with a new type and have had no problems for a long time now.