the "Mod" invovles replacing the carb and removing the fuel pump.. You can 'reverse' mod" if it needs service. (Provided YOU do the mod and not some mechanic you hire)
Page 2: Propane is less potentent than Gasoline. If you are planning on using this in a fixed location with a big tank.. GO FOR IT. but if using it portable you are better off with gasoline.
Of all the portables.. ONLY HONDA has the Extended Run Fuel Tank option. Due to the design of the fuel system it can suck fuel out of a portable tank attached to the on-board tank giving you near infinite run time if needed.