I have day-sailed and raced both the Triton and the Tartan 27 at various times in my life, including literally sailing both in a single weekend. It is not very hard to really answer the question which one sails better. The Tartan 27 is significantly faster on all points of sail, especially is you use the centerboard strategically (lowering it upwind, partially raised on a heavy air reach to balance the helm, and raising it all the way on a run). The Tartan points higher and sails better on a run. The Tartan easily beat the Triton around the race course and Tartan typically beat the Triton on corrected time. I raced on both and thought the skippers were pretty even.
Because of the smaller jibs
and chutes, the fractional rig
sail plan on the Triton is slightly easier to handle (but in fairness I am also a big fan of fractional rigs
). But in reality, with the stiff spar and deck hardware that is typically found on the Triton, the Triton really is not all that much easier to sail than a Tartan despite its fractional rig
But most significantly, the Tartan has a much more comfortable motion, both in terms of roll and pitch. I personally strongly dislike the motion of a Triton, especially in a chop. Also the Tritons need to be sailed a higher heel angles to achieve a reasonable speed which I find uncomfortable and tiring.
The build quality on the Tartans were much better and general detailing was much betterthan the Tritons as well. To me, personally I really enjoy sailing the Tartan 27's in most conditions; they are truly well-rounded designs. I would take a Tartan 27 (that is in good shape) offshore without hesitation. I would never want to go offshore in a Triton and don't enjoy sailing them in anything other than moderate conditions.
In terms of absolute speed, a Catalina 27 will be significantly faster on all points of sail than both of these boats, but they are not as well built as the Tartans and in some ways but not all, were not as well built as the Triton.