I bought a Pentax Digital, modified by Zone VI, about 6 months ago. It's about as accurate as they come. I also own a Soligor Spot Sensor Ii, and a Sekonic L508. I recently tested all three against a Kodak Gray Card, in the open shade of my front porch. The L508 was set to EV readings, and a one degree spot setting.

Upshot is that all three read virtually the same. The Sekonic provides flexibility for carrying a single meter, and I have what I consider double backup to it.