I also have the OEM Curtis/Kubota plow on my 04 900. I don't get the snow Mike does but we get enough to work the RTV pretty hard as I'll do up to 2000 running feet of driveways.
I wish I had a picture of the Curtis mount to show you. The blade you showed might take light plowing but it looks like the mount would be the problem area. The side/twisting forces generated on the mount are very high and I'd question the ability of the one shown stand up to them.
By looking at the mounting kits, it would appear that not only does the hardware look much lighter than the Curtis, it also looks like the mounting point on the 900 is the hitch socket. That's a single point that will take all the side forces from moving snow and that can't be strong enough. The Curtis/Kubota mount bolts directly to the front of the 900 chassis with several bolts and the chassis mount holds the entire plow mount by engageing the entire width of the mount and clamping it into the body mount. Two large clamps keep it there.
I paid $1700 for the Curtis mounted on the 04 about 5 years ago.
If you only get 4 inches of fluff then it might be ok but if you get 6 inches of wet snow, and are moving it on a 900 foot long drive, when you hit a rut or other obstruction under the snow either the RTV will move sideways or the blade or bracket will bend. So far, my 900 has gone sideways and the blade and mount are solid.
I'd probably save up and buy a better unit later. I'd love a BOSS V but so far the Curtis gets me down the road.
Bob