I just watched a video about Quilt top Express by June Taylor. Has anyone ever used it? I was wondering if it make a quilt top too stiff, like adding interfacing to your top.

http://www.junetailor.com/videos.htm

Yes it will be slightly stiffer. It is almost papery feeling, so it isn't real stiff. :D:D:D

So when it's washed will that stiffness go away?

I made a quilt with it, and after layering with warm and natural, it really feels no different than usual...haven't washed it yet...and it is a wall hanging, not a bed size...was really easier to use than I thought...

The finished quilt on the video http://www.junetailor.com/quilttopexpvideo.htm
looked just as soft as one made without it to me. In effect, it's the equivalent of a design wall that is stitched into the quilt! I quite like that idea.

I used something similar that I bought by the yard, not June Tailor. I couldn't get the fusible to work so ended up using basting spray. It worked great for piecing a bunch of 2 inch squares to make a doll quilt. Fairly quick and all my seams matched.

That sounds really interesting Questionable availability though it seems, Joann's online says no longer available and another site I saw was out of stock as well. Is it a new product or has it been around a while?

I've never see it before. But I don't think it's new.