This same question seems to be in 4 or 5 different posts in the last week, and my take on it is simple : if you can handle the treble after at least 50 hours burn-in (your ears and the phones), get the 325. If not, dont rely on the mystical 100/150 or whatever hours to change the character of these headphones. If there is a single burn-in myth that needs to be addressed, its that a pair of headphones will completely change in character after prolonged use - our perceptions might change, but the headphones are unlikely to go from Mr Hyde back to a mild-mannered Dr Jekyll, imo.
Personally, I can live with the rollercoaster ride, but I agree that the 325s arent for everyone.