Assuming that everything's working right (the display is set to full brightness, you've got the more recent antireflective version of the panel, etc.), then the display is very readable in daylight. More so than many LCD or LED displays I've seen.

However, if you have the sun hitting it directly, i.e., the sun's rays are shining directly on the display pixels, then it's only barely readable. Depending on your definition of "readable", of course. Some would call it unreadable in direct sunlight since you have to stare pretty hard at it to be able to read it.

I don't know where to obtain those VFD displays, but as I understand it, they're not cheap. And the circuitry/software to support it isn't trivial, either.

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Tony Fabris