Just been talking to louigimoto, and he was saying he's got some really good batteries, not gel type but the same size, and he reckons the starting amperage is much higher than the stock Ducati ones. Says they fire up his race bikes no trouble at all. Reckon I'll get one myself in the autumn.
You can catch him (sometimes!

) on 0777 5557797.
Swollen battery casing sounds like a clapped rectifier to me, though.