It's more useful and changes the gameplay for a lot of different classes. Reduction is great and all, but its uses are pretty straightforward and more defensive in nature.
Plus, if we were to say SGW and RAWs should be the same prices since they're both ladder prizes, then the mythological green wings and ice wings would be the same price too. But there's a difference.
Anyways, I still think 10% is too low even for a voting reward.
I stick with 25% for RAW, and 15% for the vote-RAW. To offset the SGW/RAW value difference, just make the vote-RAW 50% more coupons than the Fluffy Wing value.