Possibly... For myself, I can't comment on the WNW kit, but I enjoyed building the Roden Viper kit, which I did as one of Mannock's machines - there are pictures of it somewhere down in the Completed Models section FWIW.
I've just had a look at the MasterCasters site. Interesting, especially the Nieuport 17 cockpit, but I digress. To my eyes, the SE5a radiator looks slightly more detailed than the Roden one, but not by so much that I personally would have bought it.
To me, buying the WNW kit and then turning it into a Viper machine sounds an expensive and messy way of going about things, but modellers have done madder things than that. You're talking to someone who bought the Special Hobby Morane N in the hope of cannibalising it for a few bits and pieces for a Morane L. Which is still a long way from appearing.
So: I would say this actually looks like a nice project. If you used the Roden kit, spruced it up according to your taste and finances, you'll end up with a unique machine. In my experience, the main drawback of the Roden SE kits is the unsatisfactory shortcut they take with the inspection windows. You may well want to spend some very grudging time digging away at the wings and tailplanes to render something better.
And of course, no SE5 kit, WNW or otherwise, will spare you the character building thrill that is rigging one of these machines.
Go for it!
Mark
