I must admit that is one thought that's in the back of my mind. My boss has QC35's and raves about them when I pull out my old 15's, but at close to double the price I am not sure they are worth that difference (to me) and I am sure I could resell the 25's on TM and recover my cost or close (even 15's are going for $175 currently) if I did subsequently decide to upgrade to the 35's (or as you say 45's one day!), or maybe, but unlikely the Sony's.