New topical flea treatment

I've use Frontline Plus for flea and ticks for a while. I have also used Program which is a monthly pill that prevents formation of chitin in flea eggs and larvae, thereby killing fleas before they develop. Although Frontline still seems to be doing well for the dogs, I have read that long-term use of a particular product may reduce its effectiveness as fleas may become resistant. However, I haven't read any published papers to that effect for Frontline.

The other day when I went to the vets' office, I saw an ad for a new flea product called ProMeris. ProMeris is a spot on treatment, just like Frontline. It is only available through your vets' office. Fort Dodge who makes ProMeris established a veterinarian-only sales policy because it believes veterinarians should be pet owners’ primary source of information to help ensure the health and well-being of their companion animals. And it is new so there isn't much information on long-term effects.

The active ingredients are Metaflumizone that has never before been used to control fleas before. It attacks fleas’ nervous systems by blocking voltage dependent sodium channels, which results in paralysis and death of the flea. Amitraz, the second active ingredient in ProMeris for dogs, is a well-established tickicide and provides dogs with up to four weeks of tick control. Amitraz works by disrupting the tick’s normal nerve function, leading to reduced feeding and attachment, paralysis and death of the tick.

ProMeris for dogs effectively controls fleas and protects against re-infestation for up to six weeks, and may be used as part of a treatment strategy for dogs suffering from flea allergy dermatitis.

I'm not sure whether I'll switch to ProMeris or not. There are a lot of squirrels, foxes and opposums at Surry which makes for additional problems when trying to control fleas. So I need something that remains effective for the dogs during the flea season. Hopefully, Frontline will continue to be effective.