No input for the Express.
I owned a 30 MKI (5 ft draft) for 12 years. Great boat, stiff, points well and lots of fun to sail. Well built, but as with all boats, there are some things to look at during survey. The shoal draft is rare around New England, I don't think they made nearly as many. Cncphotoalbum.com is a great resource for information and the C&C email list is a fantastic forum for asking questions and getting answers in a jiffy. They are getting on in years and you can find them at (what I consider) very good prices.
I never raced mine, but I believe the 30MKI is an easy boat to sail to it's PHRF as long as you have good wind. In light air you need big headsails to stay competitive.
In heavy air the boat just digs in and keeps plugging along at hull speed, even if you have up too much sail. I never reefed my main, I would often just forego it and sail under jib alone.
I now own a C&C 30 MKII and learned to reef this boat early.
C&C Yachts have a cult following. Once you are in you don't get out. Ever.
Given the choice between shoal and standard draft, I would go with the 5 ft version unless you have a specific reason to go with the shorter keel.