Hi DP,
I have Betty Lou, a deep fin T37 (you've seen my blog). I've never sailed on a centerboard T37, so I can't speak from experience about how the two designs compare. I've read that the fin keel points a bit better, but that otherwise they behave quite similarly. As to how my boat sails, I think she's a dream. We sail of the Washington coast in some pretty challenging conditions, and Betty Lou has always handled it like a champ. This August we spent two weeks at the mouth of the Columbia River, day sailing out of Ilwaco Washington. In a one-week period we crossed the Columbia Bar ten times. The bar can be one of the most treacherous in the world and has big seas and strong northwesterlies all summer long. We had Betty Lou out on several occasions on this last trip in 10 - 12 foot seas and 25 - 30 knot winds, and she went to weather like a race horse. We never felt overmatched by the conditions, although we backed off to a double reefed main and our working jib in the biggest winds. I have an Alpha Marine below deck autopilot, and we have sailed both upwind and down under pilot for hours at a time with never a problem, even on a deep broad reach and large following seas.
Our home base is about 60 miles up the Columbia, and sometimes I envy the shallow draft of a center boarder with the board up, but most of our cruising is and will be offshore and up north in BC and Alaska, and in the deep waters up there the deep fin really shines. The boat always feels well balanced and is never tender.
Tom Wells has sailed on both boats, and I bet he'll chime in here and give you his take. I'd just say that I don't think you'll regret your choice in going for the fin, unless you are going to be doing a lot of sailing on the east coast. I know all our Chesapeake brothers and sisters like the shallow draft of their centerboard boats.
BTW, I'd like to know when and why Tartan quit using the T-38 designation. Betty Lou's nameplate says T-37.
Anyway DP, if you get out Oregon way, give us a call and we'll go sailing. Betty Lou will have a full suite of brand new sails before Christmas and they'll need some breaking in (bring rain gear!).
Here's a pair of links to some videos from our recent trip. The 1st is inbound over the bar in about 20 knots and 4 foot seas on a beam reach. The second (vertical format video) in outbound going to weather in some nice 10 foot rollers in about 25 knots.
http://youtu.be/WhSxPvi7lN4http://youtu.be/gZNhyfGQvXULater,
Jay