I do weddings as well, presently I am working with a 30D and Rebel XSi as backup. I am looking at getting the 5D Mk II as I have all FF lenses. I personaly think the glass you use is the most important thing to consider; you can have the best camera with a bad lens and your images are sure to be poor and I am sure you aer well aware of this fact. the lenses you have are fine, I use the 17-40 and love it, I also have a 85mm f/1.8 which I can't recomend as I am very disapointed with this lens performance in every respect (slow and inacurate focus, soft images) I use a Sigma 70mm f/2.8 prime which is perfect; see what Popular Photography Magazine has to say about the Sigma.....
See the link to see what Popular Photography Magazine has to say......."CONCLUSION: With a lens like this, Sigma makes it difficult for us to sound objective. In practical terms, it's faultless"
Get one!!!
You can see the link here.....
http://www.popphoto.com/cameralenses...-macro-af.html