I think trying it out on a quilt as you go first is a great idea Rebecca! It wasn't that hard on my swatches and I got good practice that way before taking it to a large quilt. I didn't find it any harder to do the stitching on a larger quilt, just the usual complaints about doing a large quilt on a domestic. ;) Bulky, awkward, etc. The same for any type stitching I've done so far. LOL
I think the loft would make a huge difference. If you were to use a heavier cotton or even a wool, you'd probably see the "poofs" inbetween the stitching better than the low loft cotton I used. I mean, you could see the design and all, it just wasn't as dramatic. The only problem I can see with using a higher loft cotton would be that it might get stiff with all the thread used. I'm not actually sure if that would happen because all I've used is a really thin bat so far, but it just seems like it wouldn't drape nice. I'm dying to do this with wool!! I hope it will still drape nicely. The only problem I have with a really thin bat, is that after all the hours the top has to spend under my warm hands and the hot machine light, it tends to soften and stretch some, and if you're not working from the inside out, you can wind up with a bit too much top for the back at the end and reallllly have to "ease" it in.