Since I own one, I can add some insight
corrosion - haven't noticed anything, my bikes serial number 4xxxx so this might be the case, but dealers bike was 3x and had no problems either. Could be that there is just one patch that has faulty spokes etc.
buttons sicking: yep, happened to me too. I used hair-dryer to get rid of the water inside the housing. This happened after a really heavy rain storm. I have ridden in the rain before, but this happened when it was just pouring
heated grips: known issue, but I asked the dealer and he said that yes they had a problem with one bike out of 10. And the bike belongs to Honda Baltic. Technician found the problem fast and said that nothing major was actually wrong. I don't know what the issue was, he didn't clarify.
rear rack - no problems there (my bike has been in day to day use since April, 7000km is on the clock)
sensor replacement - don't know, I haven't had problems
throttle control - no jerkiness. I rode friends 990 and they are about the same, maybe Honda is a little bit smoother. I was afraid that throttle is jerky and I'm happy that it's not.
clutch cable - haven't had any problem, but I read about it in facebook
I will add another thing:
RNS - I had my remote changed because it didn't work after first rain. And now after the same storm that made my SET button sticky, the RNS doesn't work either. I don't believe that Tony form RNS send me another faulty unit, I think the dealer messed up something when it was installed. I think the water can get in. I don't have any spare time right now to take the bike apart, but I will. Probably to take the RNS Tripmaster off for good.
Overall I really like the bike. Me and my friend both are n00bs in the adv world and learning to ride off-road. I have a youtube channel and I try to upload atleast once a week. http://youtube.com/fltatk
Must of my riding is with my mate who has KTM 990 Adventure