I've been nursing along the YTX-12 battery that came in my bike when I got it from JB4XX. It would work fine, but if I left it off the tender for a couple days it wouldnt start - just too lazy and too many projects for me to switch it out. Finally left me stranded a couple weeks ago, pushing starting the bike when I needed it... that's what I get for being lazy.
Anyway, my rep had been talking up these new Lithium Ion batteries which we had started selling. Customer feedback had been good, so I dropped one in.
Much smaller size battery, 10-11lbs lighter, and output seems better. I have a 12v plug pushing a dual USB 2.0 adapter to charge my GPS, Iphone/itouch and some heated goodies when I need them. With everthing working, everything has been perfect - lights all bright, chargers all working, everything toasty. Even when my Yuasa was in good shape, I never had a result this good.
They aint cheap - the 12cell recommended for the XX is $189 MSRP, but they have a 3 year warranty and have been very reputable to deal with.
http://www.ballisticparts.com/products/batteries/12cell.php