I would say absolutely there would be a noticeable difference. Espescially in any waves or chop. Also the carbon spar might actually be LESS STIFF in certain directions than the aluminum - meaning the back stay could have a much more pronounced effect on mainsail shape than the original telephone pole extrusions.
it is no wonder Tartan is currently making their own carbon fiber spars. It would be interesting to find out the cost of attaining a new spar from tartan
Perhaps for the 3400, 3600 ,3700. All are longer spars, but with the lighter weight, the 37 could handle it.. or you just take a hacksaw to the mast base....
Another neat feature on new Tartans is the "trough" boom. They are also composite material and lightweight, and allow the main to stack neatly on top of it without the "stackpack" sail cover.