I actually find lap bars (proper ones like blue fire) more secure then OTSR. I'm not to fussed either way because I trust the tech. But with lap bars, the restraint holds you in. With OTSR (with the exception of air and swarm) you aren't making contact with any of it really. It sort of just floats an inch or so around my shoulders and chest. Because you aren't held in, your head does jumble around and make rides seem rougher.
On lap bars, you are held securely around the waist. While the top half feels more exposed you feel more secure as the restraint is holding you. Rather then going around you.
OTSR probably seem more secure as they appear larger and you can see them more.
I like the feeling of insecureness though. So try and get the restraints as loose as posible.