No clue what bike you have but yours is tall to begin with. In my size the Degroot is 159. That isn't real tall.

The picture clearly shows it has plenty of clearance at the seat tube. More clearance with 28's than my Focus has with 25's.

Most are designed for at least 28's and today most have disc brakes.

Any idea of the frame's weight?

No clue. Looks like your standard DB aluminum. They're all pretty light. $808 for the 105 model and a wheelset I wouldn't need to upgrade isn't bad at all, whatever it weighs. Just looks like a good all around comfortable road bike.

Hope I'm not necroing this too badly with my first post, but thought I should mention the Alex and Drew DeGroot frames are different, like you'd see with Trek's H1 and H2 Madone/Emonda.

Alex Fit Geometry

In my size, the Alex DeGroot has quite a long effective top tube at 565mm, a 400mm reach and a 540mm stack. That makes it quite long and quite low compared to just about any major brand bike. The closest I could find, again, were the H1 Treks. Anyway, I can appreciate frames like this as I have a slightly longer than average trunk and wingspan.