I have owned my K1100 LT for almost 2 years now. This thing is hot & heavy. I rode it the other day in 60 degree weather and I could feel the heat pouring out, especially on the left side onto my legs. It wasn't uncomfortable then...but summer is coming!
I am also still trying to get it sorted out. Horrible stock seat, handlebars that come back way too far. Knees bent too much for my liking. loud motor too. On the plus side, it eats up miles, has great suspension with an Ohlins in the rear and Hyper springs in the forks, Michelin RP radials, runs smoothly and looks good, at least to me.
I have another bike, also a BMW. I have owned my 1975 R90/6 for over 32 years and have always enjoyed it. It now has around 200,000 miles on it. There are no heat issues with it. It weighs around 466 pounds wet (vs 638 for the K) and the R90 weight is low to the ground. I find the seating position and the stock seat to be comfortable as well. Will I ever sell it? NO, it is too simple and cheap to fix and maintain and is really fun to ride on all kinds of roads.
Hopefully, I will come to love my LT as/or if I get the ergo issues sorted out, but if not, I will sell it and won't look back.