I am quite impressed, especially given the amount of time you have been doing this (I was a slow learner at first, because I wanted this to just be a fun hobby for the first several years. Then, I got a full case of the knifemaker's sickness, and decided to become dedicated with the idea of doing this as a true professional now and if I live long enough to retire. So, there was a leap in growth due to pressure from my good friend and sometimes mentor JD Smith. He hasn't been a teacher, or I would be better, but he gently pushed me to take it and myself seriously. You don't need the push I did, you are already taking things seriously).
I love the handle. I do think that, if you had not rebated it, and instead drilled it or made scales and matched them in profile, you would have been better off with this particular piece of antler. Your idea for the channel milled into the handle material is a good one. It has been around for a long time, too.
If you go to Bob Engnath's website, which is still maintained even though he has passed on, there is a section about handle making and styles. He describes this method. You can find a lot of practical advice and good knife patterns at that website, too. fyi.
