Never tried Entomol. But I've found any of the essential oils simply don't work more than 10-20mins after application. I'd be very skeptical, but I'll try it if I can find an EPA/FDA approved spray.

Picaridin is safe for everyone, but follow all label instructions. Also use the 20% concentration. I find that 10%-15% is about as effective as DEET, 20% is about twice as effective (in my completely uncontrolled, unscientific, testing).