I have sailed on, and raced against C27s with standard rigs, tall rigs, fin keels, with outboard and inboard diesel engines, but not a wing keel, and agree with Jim that an inboard diesel engine will severely degrade it's performance.
With a sailboat, everything relating to it's performance is dependent on it's ability to generate speed, and it's ability to accelerate. As a sailboat's speed increases, it's ability to sail close to the wind also increases. The drag created by the prop constantly in the water prevents the boat from generating it's maximum potential speed and pointing ability - not by a little, but, to my way of thinking, by a lot. Whenever the amount of drive in the sails declines, such as when in a lull, and when you're tacking, the boat won't carry as far or as fast, it'll lose speed faster, and it'll take longer for the boat to accelerate back up to speed. In order to accelerate out of a tack, you'll have to bear off the wind much farther before you can steer it onto it's new course. As a result, it'll have a much wider tacking angle. By comparison with either your S2 or an outboard powered C27, it'll be very unsatisfying to sail.
To some of us, performance is crucial to our enjoyment of the sport. To others, it isn't so important. The choice to trade off that much performance for a swim platform is a value judgment for you to make.