In my area though, there are several paints that do VERY well. Paints are becoming more accepted
I don't think Rated Hunters are stinted against Paints that much anymore, if at all. Especially in the US. I've seen quite a few paint colored sport horses at rated Hunter shows and rated Dressage shows both, and they place really well.
I don't think you'd have any problem doing Rated with him.
Is that saddle too wide for him? Maybe I'm seeing it wrong, but it would be a good thing to make sure the saddle fits him properly, especially if he is just started under saddle. The last thing you want is the saddle to hurt his back. :)
I agree that it is hard to judge his conformation. But he looks to have nice movement! He is only three, so he will grow and mature more, as well as fill out more.
Good luck with him, he is quite a looker! And seems very willing and level headed.