The lug sails are the same for Tenderly, PMD, Skerry, or Northeaster Dory:

https://www.clcboats.com/shop/products/boat-gear/small-craft-sails/passagemaker-dinghy-lug-rig-sail.html

I have a PMD (take apart) with that sail, and my experience is that it pulls like a mule once one understands how to set it for best performance.  I've clocked her going 4-1/2 knots close hauled in a steady breeze maybe not quite 10 knots, faster with the wind free.  Surprised me, especially for such a short, curvacious boat, beamy boat.

Mine has two reefs sewn in.  The first gets used fairly often, the second once in a while if things are really snotty.  I don't know that she'd be much faster with a bigger sail.  A bigger, taller rig might make her a little faster in light air, but I don't know that it'd be worth all the extra mast length, longer spars, etc., and it could get unhandy when it breezes on.

.....Michael

Maybe the PMD Gunter rig could be adapted to a Tenderly?  I think it has about the same area as the Tenderly XP aka Lake Union Swift, though they are not the same.

.....Michael

   Got it, thanks! I must have been looking at the sloop rig when I saw more square footage. Glad to hear you've got some horsepower out of your tenderly.