I've not looked at the pictures closely enough to know how the seam shows or doesn't. If you don't like the way the heel turns out you can do a gusseted heel in crochet, the nice part being you don't need stitch holders. You know to crochet into the ends of the rows when you go back to working in the round, right? I decided I didn't like the way it was working out and I've ripped back to add some stitches to make a sort of gusset on each side before I work the flat part for the heel. Now I'm trying to figure out the placement for the increases.
Don't feel bad that it didn't make sense to you, I had to do it before I understood.
I hope you post a photo. I would when I'm done but I don't have a camera.
What yarn are you making the real ones up in? I think you said you're still using practice yarn.
Now I'm thinking that if I make the first flat row longer then work decreases I might get the same effect. Short rows from knitting crossing over to crochet and I think to try it. Who'd a thunk it?