Honestly, I think they are different kind of plane. Although both are EPP. JW is build for DS and Speed.
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The JW was designed with one thing in mind, Dynamic Soaring. Joe Wurts designed the airfoil to maximize the speed and performance of Dynamic Soaring with an EPP wing. This plane has the torsional strength to withstand the high speeds achieved while DS'ing. Now you can have the performance of a composite plane with the durability of an EPP plane. DSing is not all it can do. It is a fast and fun plane to fly on the front side of the slope too!
The JW is now available in 36", 54" and 60" wingspans.
On the other hand, the Weasel Pro and Mini Weasel is mostly classified as Fun Fly, light and still able to fly quite fast.
The Weasel's design features give it a wide speed range, great hands-off stability, and agility.The Weasel's low weight and special blend of airfoils allow it to hover in a light headwind and go fast when you want it to. It is very aerobatic in the hands of an accomplished pilot but with the control sensitivities turned down it can be great for beginners as well.
The Weasel's small size, lightweight, and durability make it a perfect contender for light-air combat on the slope. It recovers quickly from maneuvers at low altitudes and can be circled tightly. The Weasel-pro is also great for DSing (dynamic soaring) with a little added ballast. The Weasel has been flown successfully in winds conditions ranging from 4 to 40 mph on the slope.
So, if you want something for fun and able to fly in light wind conditions, should go for Weasel Pro or Mini Weasel. Otherwise, the JW.
This is just my own ideas after my oberservation at the flying site and according to the info. available at different web site. You ,may go to the site and ask some "Experienced Pilots".