I don't think 4 ounces of wheat will make a big flavor difference, but it should help, as you said, with head retention and mouth feel. Plenty of people toss a little flaked wheat into their recipes for the same reason. Sounds like a pretty solid idea to me.
If you are able to partial mash with a little 2-row, I've found that my beers have better head retention now that I do partial mashes. The pale ale I'm drinking these days leaves lace all the way down the glass. I do partial boils on a stove top for now, and only had to buy a grain bag (just a couple of bucks) to start doing partial mashes. It's made my beers quite a bit better, and lets me use a wider variety of ingredients.