I use the fluke 1587(i believe that's the correct model number) it's a meggar/meter combo. Love it. Found plenty of nuisance problems, and i use it when my reg meter takes a plunge.
I like my Megger MIT 410EN. I had an Intellipack doing the same thing and found the bearings in the blower motor had become magnetized and were drawing in particulates causing an intermittent ground fault. Had to replace the motor on that one.