I've had one of those for about 5 years and had no problems with it. I used it quite a lot on my aprilia but not so much these days, although I do keep threatening to hook it up to my DRZ....cause that battery is like one off a toy.
Do they have the same plug as an Optimate? I need a new charger but I've got heated kit that plugs into my Optimate lead and I don't want the hassle of a second marginally different lead sat under the seat.