I built my TBHs by your specs on your KTBH on your website.
I was just wondering.....
"Are there any problems with the bees tieing the comb together with burr comb, without using some kind of spacer to spread out the top bars, with that design?"
TBH require a bit more maintenance because of that issue. It is not so much a problem when they connect to the edge boards. but when they connect to the frame in front. You can always take a knife or your prybar and cut the comb connected to the boards. You will have a bit more fun when it is connected to the frame in front. You can push your knife or prybar down in between but you need to be careful so you don't kill bees and so that you don' just break the comb in a bad way.
You will eventually break the comb piece in a bad way. It happens. Cut the comb if you need to and remove the bad piece the bees will rebuild.