The super stretch bags do have a big following here... but I would choose versalite over a SS #1 in a heart beat. The versalite is warmer, slightly lighter, and packs slightly more compactly. I have been totally impressed quality of WM bags and the how quickly the recover the loft after being unpacked. The shell is light, but after a lot of use is still looks close to new. If the versalite is a good size for you, and not too warm, I would highly recommend it.
When it comes to bags, my experience is that WM and Feathered Friends are top, typically being conservative in their ratings. Montbell and Marmot also make good bags which are accurately rated, but I think they are a half step below WM when it comes to quality.
On a personal note, The versalite is one of the few items I consider perfect. I have found. It's just the right size for my 5'10" 170-190lb. The ultralight feels slightly constraining and the bands in the superstretch bother me. My only complaint is that it's too much of a bag for me most of the year. I mostly use the Versalite in the winter, using ghost down quilt the rest of the time. This makes my wife happy though, she has stolen the versalite and uses it all the time I don't. She is really comfortable using the versalite in conditions that I would roast.