There's a trade-off when you use a closed bridge, especially when trying to play above the horizontal axis of the CB, which is that those who use the shaft/ferrule/tip as an alignment tool often can't see as much of the shaft/ferrule/tip when using a closed bridge. For those people and those types of shots, a closed bridge is not recommended. In general, I'd say that those who stand up a little higher in their stance wouldn't have a problem sighting using the shaft/ferrule/tip and can use the closed bridge whenever possible and accuracy won't suffer. However, those who get very low should probably do the opposite, which is use the open bridge whenever possible. If you watch old school players, who tend to stand up more, you'll notice they tend to use the closed bridge more than open. If you watch snooker players, who tend to stay low on the cue, their primary bridge of choice is the open bridge. In the end, as with most things in pool, it comes down to personal preference and comfort.
-djb