The link to the Axis Technologies fixture is below.

http://www.fsclighting.com/fsgreenzone

I would think that individual photocells dimming the fixtures might become problematic. They use a proprietary ballast, which is probably not a major brand of dimmable ballast. Replacement ballasts/photocells may not be readily available. I'd suggest using a name brand of ballast for your customer's application.

All the lighting harvest dimming systems I've used had a common photocell, with low voltage control.
All the control wiring that's necessary is the connection of the photocell mounted in the window, or skylight, to the dimmer panel, and a #18 low voltage(0-10V, 2 conductor) from the dimmer panel, run between the fixtures to be controlled.

As a retrofit or new installation, it's really a no brainer.