Are Optimate battery chargers worth having?

Is it ok to leave permanently on charge?

Great piece of kit,used them for years now and wouldn't be without one
myself, and yes they can be left connected permanently the whole time your bike is garaged.

Yes, especially if your bike has an alarm so you dont go out to a dead battery...

another vote here - invaluable piece of kit.

Essential piece of kit that is worth to purchase when having a motorcycle.
I use both the Optimate III and the later Optimate IV all the time. Every time after riding I plug the bikes on these Optimates (365 days year round in every season, and never ever had any problems with the batteries).