I was doing a 60k service on my car and thought it would be a good idea to replace. I did just about everything else (tranny and diff fluids, flushed brakes, replaced spark plugs, cleaned air filter, replaced AT filter, changed oil, replaced leaking valve cover gaskter, etc etc etc)
The housing looks like a pain to get out, and the hoses all seem like they're about 1 ft-lb of torque from cracking, so I'm afraid I'll have a lot more to replace than just the valve