In reply to climberjamie: I'm now on my second pair of Defys but I do a serious amount of climbing in them. My first pair of Defy certainly lasted longer than the previous pair I wore out which were 5.10 Anaszi Velcros.
It's a generalisation but the higher the 'performance' of the shoe, the quicker you are likely to wear them out. The Defy is a very good mid-range shoe but I've found that velcros (and slippers) do wear out slightly faster than lace-ups. Unfortuantely, even with reasonable technique indoor climbing, depending on the wall surface, can still result in accelerated wear. Watch out for flagging on textured surfaces and repeated failure on boulder problems especially.
I've got both Defys and Anaszi Velcros on the go currently and the Evolvs get worn most of the time as they are far more comfortable. The 5.10s have a slight performance edge on very thin climbing where non-existant and tenuous footholds need to be used, but that amounted to a grand total of 4 routes/problems in a full year of climbing.
In terms of comfort and build quality I certainly can't fault the Defy and I have every intention of getting another pair in the future.