Jim, you're right about easily getting the OP in too deep. For the new shooter, or up-grading from a bare bones stick gun, an O/U may offer decisions that he may not have a clue about.
If you've never shot a serious trap gun, you may not realize a higher rib and stock allow quicker target acquisition with raising targets, but may be a detriment with crossing targets. If you'll be shooting mostly trap, your scores may increase; however, a conventional rib may serve you better for a general purpose gun.
Something to keep in mind: The extras, be they functional or cosmetic will add to the cost to the gun. If you're you're going to be paying extra for something make sure you know what it is and that it will improve you shooting, or make you really feel good about the gun. Until you know exactly what you want in a gun, keep it simple. So, if you eventually up grade, your old gun is an easy sale.