To answer your specific question, yes the REDA gas can is IMHO superior to the Walmart gas can.
The shell of the can is much heavier, and thus much stronger. It won't get squished by other stuff and the design of the cap seals tightly, so it won't leak inside your side bag.
I carried one on my last big trip, about 4000 miles in 6 days of riding down to the Dragon.
It's a very nice unit for carrying extra gas with you.
Frankly, I never used it, and all it bought me was a little peace of mind. Living on the East Coast of the US, I was never that far away from a Gas Station that I needed it. I was constantly freaked out by the red gas light coming on at about 120 miles. Now I feel very comfortable going 150 miles between fill ups.
Next trip I take I'll make better use of the saddlebag space, hopefully storing raingear for a shapely passenger.
Specifically then, if you feel the need to carry extra gas with you, the REDA is the best gas can to use, however, for myself, I don't have a genuine need to carry extra gas and can use the space more productively.
Here is a link to one source for the can. There are others that may be less expensive,
http://www.amazon.com/Reda-Portable...BVDI/ref=sr_1_1?ie=UTF8&qid=1324126506&sr=8-1
As usual, my free advice comes with a double your money back guarantee.