I've used Piezography inks for about six years. I have a 7000 loaded with the Quad ICC Selenium inks at the moment, and have a 4000. (So glad I have the 4000, not the 4800. It's truly Epson's wet dream to have you waste $40 in ink every time you want to switch between matte and gloss).
I find I still really like the Piezography inks for SOME images. I've also used QTR and IJM/OPM to try to create custom paper profiles with both printers and a variety of inks. At this point, I only like the Piezography inks when I print with the ICC Hahnemuhle William Turner profile/paper from Inkjetmall. I've yet to create anything satisfactory with QTR or IJM/OPM and the quad Piezotone inks.
On the other hand, I've created some very nice B&W profiles for the new Crane Silver Rag using IJM/OPM. I love the look and Dmax of the Silver Rag, but as with most glossy and semi-gloss papers, you get tons of reflections.
I think if you are inclined to mess with profiles for the 2400 in QTR with the K7 inks, you'll be pleased. Additionally, I believe they've done some "canned profiles you can use. To me, the real trick is finding a good K7 ink/paper combo you like that will represent how you see your B&W.