So you've run run a similar set up?
Not one of the inverter gen conversions, no.
I had a Class A Winnebago a long time ago that had an Onan generator that ran off the propane tank (it had a 40 gallon propane tank and the truck engine could run from either gas or propane). Not once did that generator ever fail to start, and it was an easy screw turn on the regulator to adjust fuel flow for altitude.
I have been considering the Yamaha EF3000iSEB with propane conversion for some time though. I like that the wiring harness is pre-wired for a remote start unit.
I see from your link, that the conversion you are looking at is not Honda approved. I seem to recall that the conversions from U.S. Carburetion don't void the Yamaha warranty, but I don't think they have them for the Honda inverter gens. Voiding the warranty would be an issue I'd be concerned about unless the warranty on your gen has already expired.
Another advantage I forgot to mention earlier, is that the propane conversion lets you easily run from a 5g or 10g tank, so you don't need to do the Honda external tank trick to get extended run time.