I've been mixing on the 240's for years. It's not like they have gotten worse just because new models have come on the market - I think they're still solid. Semi-open or open-back is good unless you need to track with then, in which case leakage from the phones might be an issue. Mind you, I've recorded with them a lot as well, so at least at "bedroom" level volumes it's not a problem either. Here's a tip though - if you happen to be somewhere in Europe, the AKG K701 & 702s are super cheap at the moment - selling for about the half price they're worth at around 150€. They still seem to be around $300 in the US though.