I think it would be nice to have both though I have never heard the SR-325. I own the SR-80's and I heard the original Grado's in 1987, I really liked them. I opted for the Stax as I liked the sound more. Get the Grado repaired and get the Stax too.
The only thing I would say is with the $100.00 difference between the SR-303 and the SR-404, get the 404's. The difference appears to be the color (Brown on the 404's) and the cable (bigger, lower capcitance). Plus there is the security in the feeling that you went with the better model and you won't be wondering, "If I had only gone with the one more expensive ones."