The biggest thing I like about the clekos is they only make an 1/8" hole and it is flat. Self tappers or tech screws warp the metal at the hole if you have to pull it apart and they make a larger hole to fill when you are fitting and have to move things a lot like door posts. I do use tech screws when I am limited on clekos or if I need to pull metal together like when I move the front of the bed pan under the seat pan, I will use tech screws since I do not have clamps big or long enough to secure things. The best thing with the clekos is mocking things up as well. I can set a cleko, pull it and shift things slightly and then just drill through the same visible hole to make a change. With tech screws you have to move the whole thing and drill 2 new holes again. Both work and have their place, once you try clekos, I do not know of anyone who said they do not love them.