Personally I wouldn't touch an HRO. Proprietory parts
makes servicxing VERY expensive, the HP pump is lucky to last 500 hours in the tropics and the original feed pump they supplied was not good enough for the job so they had to install a positive displacement
pump in its place. Service
& warranty back up from them was poor. The last HRO HP pump I overhauled using their parts
kit cost around $1000. When I priced the individual parts from a hydraulic supply place (yes, standard hydraulic ram seals
are used in their kits) the cost came out to around $150.
My pick for good energy efficient units is Spectra. If energy efficiency is not an issue Village Marine
would be my pick.
This is from my experience as a cruiser as well as an RO repair specialist (not salesman)