Not sure what you mean by reliability improvements? Mines been fine as have the majority of the bikes sold - its only when they go wrong that people tend to post about them.
Mine has never stalled. Does the stalling have something to do with old posts on removing the charcoal canister... Mine was removed so maybe that's why I have no issues? I assume the 1299 has the same charcoal canister to get rid of
Canister is removed on mine. It hasn't stalled, but it is very slow starting. It was so hard to start a few days ago that it almost drained the battery.
I've never had a charger on any of my ducks, 1098s, 1198s, 1098sfs, 1199s, and now my 1299. Never had any problems starting but they do sit in a parkade that is always at 22 C and they sit for a few months usually during the winter.