I finally finished sewing the binding on this quilt and sent it through the wash. Each block is made from 100 squares that started out 2" x 2" and are 1.5" x 1.5" finished. Each block includes 2 pieces each of 50 different prints. Four or five of the prints were fussy cut. The quilt back is 1" Carolina Gingham.
Although the quilt was made using this technique, I found that the interfacing didn't detract from the natural crinkling that happens in the wash. My 2" squares were a pretty wide range of weights (from double-gauze to canvas) some of which had been prewashed, and some of which hadn't.
I want to, again, mention that there's no reason you can't use this method to make a quilt that will be used for a blanket. It's just important to take into consideration that the interfacing will make your quilt somewhat heavier, which may actually be a good thing, depending on the quilt's use. My intention with the comment in my original post on Sew, Mama, Sew! wasn't to say that you can't use this technique to make a blanket -- just that I think it's important to consider how the added weight affects the project. I'm sorry that wasn't very clear!
I used the lightest weight fusible that I could find. If you use a heavier interfacing, your blocks will naturally end up being heavier. I don't have one single product to recommend, since any lightweight fusible interfacing should work. Just keep in mind when you're shopping for interfacing that not all products are the same weight. The best guideline I can suggest is to feel the weight of the interfacing and consider whether you'll be comfortable adding that weight to your quilt.

I've also gotten a lot of questions about why I didn't use a wash-away fusible stabilizer. I finally tested out one such product (Floriani Wet and Gone) but I was not happy with the results.* Wash-away stabilizer necessarily dissolves in water, so you can't use it with a steam iron. That's a huge turn-off for me. I just do not want to mess around with making an entire quilt with my iron dry and on low heat! I also found this product to be stiffer, and just generally more difficult to work with, than lightweight fusible interfacing.
*I should clarify that I was not using this product for its intended purpose. My understanding is that Wet and Gone is actually made to be used in machine embroidery and I'm sure it works just fine for that.
People have also suggested using the gridded fusible product designed specifically for this purpose. (Look in the quilting notions section.) I've used this in the past, and was similarly unimpressed. I found that it scorched and buckled at the slightest provocation and just didn't fuse as easily as interfacing. However, products like that have been around for years and years, so I'm sure there are quilters who use them with better results than I had!
So, to sum up, after trying other products, my recommendation is still to use the lightest weight fusible interfacing that you can find. I think it's really the easiest to work with, not to mention the easiest to find and most economical to buy.
I couldn't be happier with the way this finished quilt looks!