I have the Optimate III, whenever the bike is parked up, it's on the charger because it monitors the battery state and tops it up as needed.
What you have to remember, though, is that it only checks voltage, not amps, so it's possible (as I found out some time ago) for a battery that's dying to still register good volts, but then not have enough oomph to crank the engine and make it fire, so it's worth getting a battery load checker on it every 6 months or so to check.