They are a good bittering hop being high alpha with relatively low cohumulone, but that doesn't make them a bad hop to dry hop with. Go for it dude, see what you think. When I use citra I know that I'm going to get that citra character and I usually don't want to compete against it or else I start to question my decision to use citra at all.
Therefore based on my experience (and taste) I'd likely use less of it than I would a hop like citra, maybe 1:1:2 or even 1:2:4 apollo, simcoe, citra, but you won't know if you like it until you try it. I love simcoe as a dry hop when it is very fresh. Big fresh grapefruit fruit with lingering tangerine/orange notes on top of resin though I find it stores poorly and rapidly turns into a more bitter grapefruit peel and resin.
