Hard to be sure what you mean by "knuckle of thumb" w/out seeing a picture; you mean the big knuckle at the base of your thumb (closest to hand), or the second knuckle, near the tip of thumb? I use the knuckle at the base of my thumb to hook in behind the corner of my jawbone, but my middle finger is still in the corner of my mouth. To put the feather in the "crook" of your nose, you must be anchoring higher, maybe with the third finger in the corner of your mouth (at least, I would have to do that to get the feather there). Anyway, your anchor is very personal, and I don't think anyone can say for sure what is going to work best for you as an individual. I don't think your anchor, as I picture it, would feel good to me, but that's got nothing to do with whether it works for you. You can have a good shooter watch you shoot and determine if you are collasping, etc., or video yourself and watch it to determine this, but I don't think there is anything wrong, per se, with where you choose to anchor. The only problem w/ a really high anchor is that it does make it harder to properly use back tension; the advantage is that it puts the arrow closer to the eye, and usually that helps instinctive shooters with accuracy. I say, use what works best for you.