Alan Ross mentions the meter here:
http://www.alanrossphotography.com/ar20/techForum.html
I have used the meter for years. It's a little bigger, at least thicker, than pack matches. I like it very much, but I should say that it has a different feel from the Pentax spot meters that so many of us are familiar. As there is no viewing lens, sighting is by viewing through a hole. There is a certain 'windage' to this, but a freedom, too. It is easier to walk about and take readings. Somehow I find it liberating not to be looking in a viewfinder through a little circle.
As the meter is so small and unassuming, it can be used anywhere without people thinking (sadly) that it is a gun. No holster on your hip. It is small enough to hang around you neck or put in a pocket. Built like a (little) tank, from a solid block of aluminum with the electronics and optics stuffed inside. I'm sure you can drop it without problems. I think you could run over it with your car and it would still work.
It is spectrally adjusted for BW films, so filter factors and the like may be read with the meter. I have never had a meter with this feature, but I like that more than I thought.
I've heard the price is $399, not $450. Availability is a bit of a problem, but getting better. Call directly. Don't trust the email.