I would say it's still worth it for a couple days. I usually only do it for around 1-2 days if I know it was a ph problem and in the 4-7 days range for overfeeding. We understand the difference between the two but the plant sees it the same way essentially.
In the case of overfeeding we are letting the plant use up what it has stored up and getting it back to the point where it is wanting everything again. With PH I still like to do it because the plant still has a nute build up in it but it never seems to be as bad as if you were overfeeding and since it is so easy to fix PH it doesn't require as much flushing time.
I had some problems with PH during my last grow and it was causing nitrogen toxicity and pushing into some manganese deficiencies because of the toxicity happening and I feel like flushing with the pure PH'd water for a couple days helped the plant to stabilize quicker.
edit http://www.amazon.com/Kerick-Valve-M252-Float-Mount/dp/B0077RAUTA/ref=pd_sbs_328_2?ie=UTF8&dpID=21IEvJlhdgL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&refRID=0KE6B360DPNR4N3H0YYY you can get the float valves from amazon for about $8 with free prime shipping. I don't usually have luck at home depot when i'm looking for grow parts but i am lucky enough to have a few hydroponic store in my area which are usually around the same price as amazon.
I ordered these on amazon for $7 to set up a mixing station.