i'm using a similar one, but mine has an LCD display showing the 3phase ac rotation direction. Solenoid is helpful, as you mentioned the ghost voltages. But mine seems to draw less current, as you can measure phase to ground without tripping a 30mA GFCI.
i once had a line where you couldn't separate on and off condition with the neon lamp screwdriver. the cable was in a plastic conduit parallel with some 20 others for a lenght of ~60ft and collected enough strayfield to light it up in full.
