I could be mistaken but some users have reported a goodwill replacement side stand from BMW. The later stand is easy to spot as it has a bend in it and the bikes tips over much further - in fact too far, it needs a foot to lift it up 1/2”.
Re: 800 vs 850: JJH is pretty much spot on. Personally I find the engine much nicer, as the 800 has a lot of vibes due to the novel but not entirely successful layout with both pistons acting together and a counter/bob weight on the crankshaft. Other improvements are the much lighter clutch (although the 850 has a disconcerting sticky feel when new that slowly disappears with miles), no more burning your trousers on the left side of the bike as the exhaust has moved to the right side, better LED headlamp, tubeless rims, lower seat height, the ability to take the same vario luggage as the 1250 (on the 750) and more up to date electronics (I was never a fan of the old clocks). For me the 750/850 are better bikes overall, but the downsides are that they can feel heavy to move around the garage, wind buffeting is still a problem, as it is on the 800, and the brakes and suspension are no better - the GSA is > £13K with bog standard, cheap, unadjustable front forks isn’t good enough. If Triumph can put fully-adjustable front forks and Brembo Stylema monobloc callipers on the new Tiger 900, why BMW persists with the crappy 2-pot sliding callipers that just about stop the bike, is beyond me.