If it's the same ingredients as Frontline, I don't see the difference. I agree that Sergeant's has a bad track record, but I'm sure that Merial and Bayer make some dangerous products as well. it's up to the buyer to research ingredients. I think I'll probably wait a while, let any possible problems surface before I use it, but on paper it looks good.
I'm sure Merial is quite annoyed that their patent ran out and now anyone can use fipronil in their flea products, but that doesn't mean the other products are less safe than Frontline.