I bought a Shorai last May. Has worked well for me. I like the small size of it and the fact that its acid free. Yeah, its more expensive, but I thought I'd give it a try. In cold weather, I just turn the key on and let the battery warm up for a few minutes (per instruction manual) and I'll hit the starter and boom, it starts.
I don't plug it in to a battery tender. It holds its charge wonderfully. Problem with the Battery Tender is that it won't go into float mode while plugged into the Shorai, it just keeps charging. I didn't want to spend another 80 bucks on the Shorai charger/tender.
I had to use almost all the foam they supply with it so it wouldn't bounce around in the battery compartment.
I'm happy with it.