It took me 5 years before deciding to try Grado.
Why? Maybe due to their expensive MSRP and the relatively high resale price of used units. Many of the review posts identify the "Grado sound" as unabashedly colored, too, and this may have been the biggest deterent for me.
That said, however, I'm glad I finally took the Grado challenge, but only coming about AFTER trying Sennheiser, Beyerdynamic, AKG, Ultrasone, Sony and Audio-Technica. Who knows? Maybe it's a secret aversion to a U.S.-made headphone! (Although my very positive experience w/the Etymotic ER-4S should have convinced me otherwise.)
Although I am still enamoured of my RAL/K701--which have handily beaten all popular, mid-fi headphone contenders from the ranks listed above [i.e. HD580/600/650, DT880(2005)/(2003), ATH-AD900LTD, Ultrasone HFI-2200, PL750/2500, Sony MDR-SA5000, AKG K501(?)--add Grado SR-225, MS-2, and now working on SR-325i(?)], Grados represent a highlight and a pleasant surprise along the way.
My alltime favorite headphones tried to-date include Grados:
(#1) RAL/AKG K701
(#2) RAL/Proline 750
(#3) {a very close third} Grado SR-325i
(#4) DT880(2003).
. . . Not bad for a stock set of cans contending with two appreciably more expensive, re-cabled versions.