EILs work great, provided you install them
close to where the heated water is needed...otherwise, you'll be paying to replace the heated water that is sitting in the pipe(s) downstream from the heater itself...
I went and insulated all the hot-water pipes from the heater to the destinations...made a BIG DIFFERENCE when it came to using the sink/faucet anywhere from 15 minutes or more after it was last used...the pre-heated-sitting-in-the-pipe water was still a bit warm from the previous useage...
At work, we installed one unit (fairly small) in the men's room, T'd the output to feed into the women's room, then changed out the faucet aeriators to restrict the flow down to 1.3gpm. That way, we'd still be able to have BOTH faucets open at the same time and still keep the water temperature at 125° as set on the unit itself.
The only concern you might run into is the mineral content of your water...if that should be a concern...then you can always install, pre-heater, a filter that is specifically designed for your filtration needs. That will help cut down on crud-buildup that would occur, much like the internal buildup you'd get with a regular waterheater.
Good luck w/the install...
I know the folks at work enjoyed, finally, having SOME hot water after so many years of crappy, tank-located-85-feet-away, tepid water...
