I'm collecting some pay monday, and would like to do the same. If I get it done, I'll let you know how it turns out. If anyone else has done it, I'd like to hear their thoughts on it too.
I've heard great reviews on them, but also that several people trying out the tandem peeps end up taking off the front peep in the end, and going with the original post.
They look very well made and of very high quality. Plus, as far as I know, they're the only ones who make this type of site for this type of rifle.