I'll echo what's been said before. I do a lot of applique quilts and use the Lite version all the time, it's relatively easy to sew through. It leaves the quilt somewhat stiff, but that's not a problem for my wall hangings. I accidentally bought the Ultra one time and I'm still trying to use it up! Ultra is difficult, but not impossible, to sew through and much thicker than you would need. I've used it occasionally to adhere thick embroidered patches (like Girl Scout badges and the like...). I really should just toss it.
That said though, I agree that for a t-shirt quilt I would recommend fusible stabilizer instead of a product like Heat 'n Bond. Unless you're doing some small appliques on top of the shirts? Anyway, best of luck with your project!