Here's the deal.

When I did what you are thinking about I found that at 30c I couldn't keep the tires as soft as I like
without the rear wheel jumping around in corners. Btw, I am a big guy, so if you are under 200, this
might not apply so much. I also like to keep the tires as soft as I can without creating other problems.

28c is a great size for a lot of people. I ran Rivendell Ruffy Tuffys for years and loved them. Then the roads
around here turned to crap.

Lots of good tires in that size. Vittoria has a couple new tires, the Randonneur Hyper and Pro. I am planning on trying the Hyper
this year, but in the 35c size.