I may comment on some things?
First of all, high cheek bones are not really a gender marker in themselves - as can be seen by looking to Korea where women get their high cheek bones reduced to be more feminine. It is more a thing of beautification. However, high or strong cheekbones contribute to a more "stretched" facial skin and tissue. This makes for a more youthful appearance even with some age.
Regarding the choice of method - I am not sure whatreborn means with "permanent fillers" - so far I only know of silicone as a permanent filler and that is usually a bad idea. Other fillers eventually will be going away. Fat transfer is a bit of a game of luck - maybe it catches, maybe it does not - between 0 and 80% of the fat can stay in the long run - if it is 0 or 80 depends on the body, hormones, the skill of the surgeon and the technique. What should be impossible with fat grafting though is that the fat "moves" as Moni said - this is because it is not the fat that is transferred, but the cells who store fat. They should not be able to travel. However some surgeons probaby destroy a lot of the fat cells, liberating the fat/oil from them and the oil can travel, of course - this is quite a bad complication though, it should not happen with a skilled surgeon. Implants are probably the best choice in terms of how well it can be planned and for long term stability - they will never go away and if they are of the type that is fixed to the bone, they also will not move. But of course its an implant - a foreign material in the body and can cause reactions of the body. Also there has to be an incision and the place for the implant has to be opened surgically, which can cause complications like problems with healing of the wound inside the mouth.
My personal preferrence would probably be fat grafts, done by a skilled surgeon, maybe do it 3 times to build up enough cells that really stay. But that is for me personally as I hat implants generally and because I already have strong and high cheekbones naturally. If I would not have them, I might very well choose implants.
I am also scuba diving by the way and I dont know if my cheekbones make a difference there - if one finds a mask that fits, it should be ok. I am more worried about the future of my diving when it comes to the forehead surgery and the changes of the frontal sinus...