I have very long (about 1cm free edge) NNO nails with a very high natural C curve. I can put Minx or Blixz on my clients' finger and toes with no problem. However the shape and length of my own make it just impossible. I have tried for hours and I just can't get if crease free! My pinkies are the most difficult - they are almost like claws if you look at the side on!
I don't think the length is the problem, its the curve, as I have clients that have longer nails than mine that I had no problem with.
I also do not offer Minx/Blixz anymore for fingers - it just doesn't last long enough. I personally don't think Lumos makes it last any longer. I don't want to offer it under a gel polish because I don't see how I can justify charging a premium to use each product separately, but then using them together at no extra cost iykwim. I do loads of Minx/Blixz toes though where it is fab, long lasting and good value for the client and my business.
I suggest you have bit of a practice on a few extreme curve tips, but it might not be easy! Sorry, I have been very little help!