The Trident 13 is about 10 lbs lighter and about double the price (new). My guess would be that weight will trump price. Longer is going to be easier to paddle, generally. Used will sometimes have some rigging already installed.
I have studied both boats, and am more impressed with the OK Trident, although I don't own either one.
I like the layout of the Ascend better.
Good luck, and let us know what you decide.
"The cheese in the mousetrap is ALWAYS free"