We did last summer (in the Boston area) and rotated it out with some other flea products, but upon reading more I decided my problem MIGHT have been that I was getting most of the drug on the hair, not on the skin.
There was a thread here asking about Frontline not working, and I posted the above (at more length), and several people confirmed that Frontline does have to land on the skin in order to work properly. Are you sure that's happening?
I continue to use primarily Frontline because there are only 2 cat products that also control ticks, and the other one has scary numbers of adverse reactions among the Amazon
reviews. (They're not unknown with Frontline, but less frequent.)