I have both wings but I have not gotten the OxyCheq wet so I can't say much about how it dives.
The DSS LCD 30 wing is a horseshoe while the OxyCheq is a torus. The DSS wing is about 2" taller and they are about the same width.
The OxyCheq wing is intended to be bolted to the backplate and the cambands loop through narrow slots. You can't remove the wing from the plate without completely unthreading the bands. Well, you could use a STA (Single Tank Adapter) but there is no reason to do so. The wing provides a couple of ridges to align and support the tank.
The DSS wing has a couple of wide windows through which the cambands are routed. The bands are threaded only through the plate. This way the wing can be easily removed from the plate and stored separately.
The DSS wing uses rubber nipples through the holes in the backplate to align the wing but not attach it. The tank holds the wing to the plate.
The DSS wing also has a couple of anti-roll blocks to keep the tank located. These are much more serious than the ridges on the OxyCheq wing. The DSS wing is not intended to be used with an STA (AFAIK).
The center outlet of the DSS wing makes venting more predictable. It also precludes using the wing with a double hose regulator. Hence the OxyCheq wing (and the HOG wing).
I am very impressed with the DSS rig. The backplate is a class act all by itself. The LCD 30 wing just adds to show.
The OxyCheq wing is somewhat less expensive (by itself). i got mine at AddHelium
Oxycheq Mach V Signature Series A very good place to do business. I have also bought the OxyCheq SS backplate, SS Travel Backplate and the Ultra Lite Travel Backplate from them.
I really like that Ultra Lite backplate with an Al 50 for just relaxing in the pool. No wing, no weight belt (just a couple of pounds on the waist strap).
You will be very happy with the DSS wing. I am...
Richard