I've had two Oddesys, the first failed just before the two year warranty was up and was replaced without any quibbling, the second failed just after two years.
Both just suddenly died under load, without any warning - start fine one day dead the next.
I have three Motobatts, all are performing as good as the day they were fitted.
The small 51914? size in my 1000 cc high comp G/S spins it like a sewing machine, no need for anything bigger on a airhead.
My local shop stocks and sells nothing else, claims they are the only battery he has never had a warranty claim on.
In Oz they are almost a third the cost of the Oddesy, and any independent test I have read shows them outperforming every battery in the test, including the Oddesy.