The reason everybody goes to WP conversion is that this is very known, good and reliable solution. Since owners of other bike brands do the conversion to WP front, only reasonable conection was that you do it on Yamaha also.
The option with WR (I think also YZ) on Tenere was not "discovered" long time ago, so it is not so often used yet, also because that was not known solution.

First link of my friend named Nacho is the first such modification in Slovenia. He had quite a lot of work with it, since he had no one to learn from. I consider this as a pioneer work. Second link is from a guy from Spain, and he did such conversion before Nacho. So Nacho only saw pictures and saw, that this could be done, but how and if it will work properly, he did not know until he did it on his own and learn on his own. So this info is quite new I guess.
Maybe someone reading this, will know about those kind of conversions done from someone else....but I am not familiar with.

Look at the prices....

http://www.ebay.com/itm/yamaha-yz450...7a21b7&vxp=mtr

http://www.ebay.com/itm/YZ426F-YZ450...d33b41&vxp=mtr

http://www.ebay.com/itm/YZ450F-YZ-WR...fdb740&vxp=mtr
http://www.ebay.com/itm/01-02-03-YAM...595318&vxp=mtr

http://www.ebay.com/itm/Yamaha-WR450...4a4d56&vxp=mtr