I used to use it every now and then, when a song was fast and I didn't have a bass player, but recently, ever since I started doing some dexterity exercises, I'm finding it easier to play in those keys. Now, A and E are the only ones that I can't do real effectively, at least not the way I like to play. If there's a bass player, though, I can play in all of them equally.
Try getting the Virtuoso Pianist in 60 Exercises book by C. L. Hanon. This is helping my dexterity a lot. I just ordered the Jazz and Salsa Hanon books too. For me, I can play well when the timing for both my hands are together or about the same; if they're extremely different then I have struggles in some keys.