Good counsel, Ann. I've certainly considered all of the trade-offs. And you're quite correct to be skeptical of bmsbattery.com: prices are good, but customer experience has been mixed, to put it kindly. I've no personal experience, so it's not a recommendation. But given the Chinese heritage of the XB-300li, it's obvious that these battery packs come from the same source, and it certainly appears on the face of it that they'll interchange on the bike without need of a grinder.
That said, even with a change-out of battery, controller (hope the replacement fits in that little box) and rear wheel motor, that's investing close to $600 in a $600 bike, rarely a wise move. The open question is how much of a performance gain would such an investment net?
Wish I knew. Wish I could get the info from, like, anywhere. But it's not to be had.
Range is really not my issue. Obviously, more would be nice, but it wouldn't much change the experience. But a few more mph across the board would have great value to me. Would an upgrade do that? I've found no clear answers to date, and not for lack of looking.
Still, not unhappy with what I have, so if all I do is risk using bmsbattery.com as a resource to replace OEM parts as needed, it's still worth knowing they're there. I have not found ANY other source for the significant power parts of the X-treme bike products.
You refer to "info from X-treme's tech" like that's something that could be had...how would I get that?