I have a couple. Bought them a couple months ago to see how well they worked/differed.
The blue one is the Smart Gun Pro V2 by HVG2 (exclusive to Fry's stores?) and the plain white is the pistol portion of the "Combined 2-in-1 Light Gun" by UNNAMED CHINESE FACTORY found all over eBay and other gaming import stores. The short distance between the trigger curve and the rear curve is about 2-3/4" on the Smart Gun Pro V2 and 2" on the Combined 2-in-1. You have to pull the Smart Gun trigger 1/8" before the B-Trigger on the Remote will register, while the Combined 2-in-1 requires a 1/4" pull.
Both shells can neatly hide Remote wrist straps. And if you're graceful, you can hide Nunchuk plugs without taking off the wrist strap.
Both include notches for the Nunchuk cord to pass through.
Lastly, bumpy-sights are on the shells. The wide "U" notch on the Smart Gun is easier and more comfortable to look thru, but the narrower notch on the 2-in-1 helps minimize deviations when visually aiming.
The gist: mileage and comfort will vary with these from person to person. The presence of complete sights and designs allowing the wrist strap to be hidden are what attracted me.