I've never used anything but bob traps. If I were to use any different traps, it would be drop traps for electronic or stall traps for manual clocking. I don't have any interest in sputnik traps though.
I do race, but I use a manual clock. The young bird loft has a space cut out in those dividers so a pad can slide in there, if I ever chose to go ETS.
By the time racing season comes around, my birds are so used to the bobs that they don't slow down for them. Sure, having an open hole would probably save me half a second, but usually if my birds want to go in, they go in. The stalling that comes on race day normally results from paranoia of hawks, but once they know it's clear and hit the board, they go straight in.
Crazy Pete, the first picture was before I put birds in, haha
We just built that loft last spring.
And lastly, as far as predator protection, yep. If you look closely in the second picture, you'll see the flaps are up above the traps and hooked to the wall. I just unlatch it, and it swings down over the door. It's a nice heavy solid piece of wood, so nothing's going to get in through it.
With the young bird loft, I don't have a cover to put over the bobs. However, there are little rings on both sides of each trap, so that I can slide a metal bar (about the same thing as the bobs) across, to keep the bobs in place. That's mostly to keep the birds from getting in. Predators won't get in anyways, because my landing board folds up into a built-in settling cage. When it's closed, the loft is safe, unless it can get through hardware cloth.
Here's a couple pictures to show what I mean by that. The first one was before the landing board/settling cage front was put on. But it hinges right on top of the aviary.
And you can see the 'landing board' that flips up, above in this picture.