I recently had an opportunity to look over and use an Adrenaline 3-season bag. Very nice, lofted like crazy, the hood fit like a dream, it felt really good inside and the center zip is, as you suggest, an extremely nice feature. I especially like the waterproof Pertex head and foot zones - a brilliant idea. As a 3-season bag, I did find myself wishing the zipper was longer, as having the ability to zip down to say, the shin area, and use the bag as a quilt in the warmer months, would have gone a long way to increase the usefulness of this bag. For that reason alone, IMHO, I think it could be recommended only for extremely cold sleepers, those who also own summer bags, and/or only backpack during the extreme of the shoulder seasons.
In a 4-season 0 degree bag, I see no loss of functionality for having the reduced length zipper of the Adrenaline bag. The hood of the Golite is quite a bit nicer than WM bags (I have an Ultralite and love, love, love it, but the Golite hood is better), so I'd say you can order either without regret.
One thing: the WM Lynx is rated to -10 degree F, while the Golite 4-season is rated to 0 F and weighs about 4 ounces more. If money is no object, and you see yourself reaching down to below 0, then the obvious choice is the WM.
Oh... the reason the Adrenaline bag weighs more is due to the materials Golite uses. They have committed themselves to using recycled fabrics for "green" reasons, and the reality is, those fabrics weigh a bit more.
Both are really nice bags though.