Currently I have standard lead-acid batteries in both our Ws and they are doing quite well.? But when my wife's W battery started to fade the bike just died in the middle of a ride.? So, I appreciate the concern.? I have a Shorai lithium in my Bonneville and I must say it is worth the price.? (Paul 'ain't kiddin', it's twice the price). But (especially in the Bonneville-which eats batteries for breakfast-well worth it.? I would not hesitate to put one in either 650 and will do so the next time I have to change the battery.? But don't go cheap.? Save your nickles and get a good one.
BC