I am a 4000 user--moderate print volume--for whom upgrading ain't gonna happen soon. Since I print 98+% B&W on matte fine-art papers, I have no compelling reason to ditch this printer. (If anything, I'd probably go with the 7800 and keep the 4000 with one of the new 3rd party inksets devoted to B&W only.) But I digress.
Try spraying your print with Premier Art spray or the Marshall equivalent. This should reduce the bronzing markedly if not eliminate it entirely on some papers. The sprays also improve the print's durability to handling, and maybe their archival longevity if their manufacturers are to be believed. I actually had someone place a drink onto a sprayed proof print; I blotted the condensation ring off quickly with a paper towel and resprayed the print; no perceptible damage resulted.
Another paper I've tried is the Crane Museo Silver Rag. A beta tester friend sent me a sheet to try out; I had some bronzing (B&W image) but not very much, and the spray eliminated it. The lustrous deep blacks of this paper really grabbed me. I intend to make frequent use of MSR, as well as similar forthcoming offerings from other makers, as soon as it's available in sheets.
I've used Red River Ultra Pro Satin with good results; again, spraying helps.