I've hit the sandbar at speed on foil a couple of times. It hurt me a bit, but the foil and board remained immaculate. However I do have a plate mount and two fin boxes on my board.
I used the back straps when I started, but taking them off means you can put your back foot wherever you want - which makes it much easier to control the lift, and you can also move it inboard easier. Nicolas goyard does not use back straps and clearly it works well for him, so I tried it too!
I have done some fast tacks, but it can be a bit tricky. Most of the time I heli tack (or gybe) because it’s much easier to keep both feet behind the mast