[Faster]

They will be very similar, especially if they are within a couple of years of each other.

The serendipity hulls were built in New Orleans primarily as race boats. Any that have what you consider to be cruisable interiors have likely been modified.

The Contessas were built as production boats, with an eye to a different market. As you have noted the deck and interiors are quite different, it's possible that the construction techniques and materials differ as well.

Old race boats always sell relatively cheap.. it's a way to get a lot of boat (and good deck gear) for your money. But pipe berths, empty caverns forward of the mast don't sell well to the cruising set.

The good news is that the race boat won't have any molded liners, so if you're so inclined, you have almost limitless options with respect to updating/rebuilding/redesigning the interiors of these boats. Many of them though will not have cockpits that would be comfortable for cruising.

I should perhaps add that we owned a Choate 40 (with similar raceboat heritage) for 12 years. It had been somewhat "cruisified" when we bought it, and over the years we upgraded and improved it more. In the end we sold it for nearly what we paid originally (not counting upgrades - but still - 12 years of use and enjoyment factors in)

I strongly believe that we had a much better sailing boat, with better gear than we could have had in that size range of production boat for the money we paid. I would not be reluctant to go that route again providing the builder was reputable and the boat had not been abused or neglected.