Has anyone tried the 4500 line, especially the 4507 with dual supervisors engines (sup iv)? Has anyone had any experience uplinking these to 3550-SMI switches? If so, what was you version of firmware? I'm think of trying the 4500 with a sup iv but I would like some references first. I had some bad experiences with the 4006 and I am little nervous about these lines. Any info is appreciated. Thanks.