Well, the success is kind of speculative at this point, as I have not actually had Andy try the gloves on, but... I did it! I finished the glove-mitts for my brother-in-law! I even have pictures as proof - incredibly shaky, blurry proof!
I had to re-start the second mitten-top because I forgot that, in order for the tops to work, I would have to treat them as a mirrored pair instead of being reversible like the gloves would be without a top. I actually got in about 18 rounds of knitting before I tried it on my right hand and immediately thought to myself... "Uh oh." Luckily I was having some sort of period of clarity, and picking up the stitches on the other side of the mitt was actually fairly easy, and starting over wasn't the drama I thought it might be (or made out to be in my Facebook status message... heh).
The first mitten-top - on the left glove - was really awkward and misshapen. I attempted something like an anatomical sock-toe, trying to accommodate the shape of the hand, without really thinking about the comfort-factor of a mitten. I had also tried to look for a mitten pattern online that might be helpful, but I just couldn't find what I needed. So I took a look at one of my standard beanies, where the shaping is circular but if you lay the hat down flat it will curve at the top instead of having sharp slopes. In that fashion, I did some gauge/measurement stuff, and figured out how to do a series of decreases at the top that was more like the top of a hat, and it really seems to work. You get that nice, oval, typical-mitten shape at the top (no weird angular bits!) and it still accommodates the fingers. I did take notes at this stage, but I'm also documenting here for future reference!
Hopefully the gloves will fit and the, uh, brilliance of the mitten tops will exempt me from my Christmas-gift tardiness. A gal can dream, eh?
Having crossed this one off my list... it's on to the next round. Next up: Rachel's cardigan, Anna's glove-mitts, and a commission for Etsy as soon as the yarn comes in the mail! (P.S.: I listed two new hats on the store... Fairy Floss and Hamilton. Check 'em out! :) )
Additional pics of the gloves: one with the top pulled back, one with the top on: