Just to balance out some of the moaning and negativity we occasionally see on this forum, I feel I should publicly recognise 2 companies here for their excellent warranty service.
The first is Hope (naturally!) who just replaced my 4 year old Vision 2 battery FOC. All the more impressive because the issue was mainly self inflicted: I'd tried to improve the contact on split connector pin, broke it, then left it lying about and managed to trap it in a door and mangle it beyond repair.
The second is worth a mention as I saw a thread a while ago questioning their warranty. 49 weeks after purchasing a C&B Seen unit, the connector on the battery broke off in my hands. I got sent a new battery, again FOC, and a picture of how the manufacturer had changed the design to address this fault.
All I need now is my broken wrist to fix itself and I'll be able to put them to good use!