I have two rigs. For taking up minimal equipment on the boat and having something that I can just "pull on and go in" with single tanks my ProQD+ is tops FOR ME. I used it last weekend wreck diving with steel HP120's on the Saturday dives (our dives Saturday were all about 100 ft. and we had the charter operator's small boat) and had plenty of air. It is weight integrated so I don't have to keep a weight belt. It has pockets, so I don't have to clip all my emergency equipment to me prior to going into the water and unclip it when I am done with the dive. None of the BP/W divers out of our shop have a BP/W for single tank diving. The space consideration is admittedly probably due to the fact that it is single tank instead of the doubles on my other rig before any one cuts in on that.
For diving below about 100 ft. in cold water.... I have a Dive Rite rig with Classic Wings, deluxe harness, and steel backplate. My tanks with this rig are dual steel HP100's. Again, I normally come back after four dives with more than enough to tick me off about having to refill over 1000 psi of air. (Of course, I cheated a bit and used my stage bottle at safety stops). It is great for deep diving. I need to clip much of what I will use on me anyways. It takes a fair amount longer FOR ME to get into this rig than my ProQD+, but I love the peace of mind that doubles give me for "serious" wreck diving or deep diving. Like many other posters here, "wreck diving" to me means poking around the outside of the wreck and peeking my light into nooks and crannies and not going inside. Oh, the doubles and steel backplate add enough negative bouyancy that I still don't use a weight belt. I rely on my drysuit as the second floatation to get me back up.
Both have their advantages, but I can see where for simplicity of using only one basic rig the BP/W have it right. I just like my set-up the way that it is and don't see the need to change what works.
Just my opinion, take it or leave it as you wish!