I've only worked with them once, with the sour form known as xoconostle (bought at Pete's Market). I tasted it, and with the sour, fruity tang, figured it would go great with strawberry in a pie. Perhaps not the conventional use of the fruit, but it worked out great, and I would definitely make it again. I don't recall having any issue with the seeds, so I wonder if tunas are different in this regard (other than just being sweeter) than xoconostles.
Strawberry-xoconostle pie, c. 2004:

(As you can tell, I'm not much for baking. Yummy, though.)