My compressed neoprene drysuit has attached boots which are the same size, material, and thickness as a regular soft-rubber soled wetsuit bootie. In other words, it is not thin like on a shell suit. I use them with size XL jetfins.
That being said, my foot size is 12, so would a size 12 Trek Book fit?
LUIS C I don't use my bare Treks for a dry suit since I live out in the tropics, but when I did get my boots for a size ten it was actually a lot larger than I thought. Hence it went to my son who is a size 13 - 14 depending on the brand. I recommend measuring your built in and send it in to help with your choice. I do have to say though that my son wears his boots for every dive, and has no issues with them. good luck on your sizing issue.
CHARLES W My drysuit is made the same way yours is and I also have a size 12 foot. The size 12 boots work great. The material has some give which makes it an even better fit. I have both the DUI bots and the Trek Boots. I think the Trek Boots have the best fit and comfort. As for your fins, the XL will work fine if there was room left when you have you normal wetsuit bots on.
EDMOND T I love my size 12 boots, they are comfortable to walk in.
ZAMIR T No, a size 12 would not fit. In your case it's hard to say but I would guess a size 14 would be more likely. I had a normal drysuit and I went one size up. As I said this is only a best guess.