For ONLY the items you're talking about making....the reverse is probably a luxury that you can justify omitting. BUT....like Ferg said, it's so dang convenient. If you eventually move into doing some harnesses for animals, even if it's just on a custom order basis, you'll love having it. There's also the distinct probability that once you start selling things that are made on a heavy stitcher.....people will show up wanting to know if you can repair X.
In the long run, if you can afford to go ahead and get the reverse option, you'll be better off.
A perfect example: Earlier this morning, I was finishing a custom sheath. The belt loop needed stitching, so I readied my new-ish Tippmann Boss, and ran a line of 4 stitches. Then over one, then eyeballed the spacing for the second line going backwards because I couldn't swing the body of the sheath inside the small throat capacity. Having a reverse capable machine would have meant perfectly spaced stitches that match the ones below it.