On rough water, like LOZ where I fish, the OA boards perform better due to keel weighting and at slow or no speed they will not flop over on their side and submarine like the YBs. Rough water is also where the flags make a difference but they are not a must, just a huge convenience. A word of caution on sliding boards, I have lost a few good fish when a board worked down the line into the hook and dislodged it before the fish was in the net or when the board hung on the net preventing a clean pick up and that is why I use the swivel. When crappie or walleye fishing I usually rig dual release clip and line wrap to keep the board in place.
Boards are a great way to cover more water and some days a fish will not take a bait directly behind the boat, especially when they are feeding shallow but they DO take a bit of work to fish effectively and can be frustrating at first. Like any tackle we get what we pay for though and a good set of boards properly rigged is expensive; if you won't use them much high end tackle may not be worth the money. If money is an issues start with a cheap set and if you think they are for you after using, upgrade them later - that is what I did. If you don't want the hassle after trying you are not out much. With that said, the only time my YBs w/o flags hit the water any more is when I am running multiple sets of boards and don't have any more OAs w/tattle flags.....
Mike