Finished the knees today. I've used DarkSide's fantastic aluminum knee darts (C4 style with the ridges). and backfilled the cavity with bondo before hand to give a space to drill into.
I was thinking of a combination. I'm going to wait till i get a flight suit but I figure the elastic strap is cosmetic more than anything. I was going to start with some snaps on the sides and if need be add a strip of velcro to hold it all together.
This armour is basically done until my gauntlets arrive in october. I managed to extend the cod and butt plates with some sheet acrylic, a blowtorch and some bondo and it turned out really well. I've also done the knee attachment with snaps and will probably do a couple of snaps in the codpiece too because i can't get it tight enough.