I was wondering about calibrating the Eye-one Pro....

Precisely WHAT is being calibrated ?
It is said that you cannot exchange you "white tile".
That clearly means that the "white tile" is used in conjunction with the tungston lightsource within, meaning: the tile is used for reflective measurements, most probably it's the lamp the drifts.

When measuring emission the lamp is not turned on. When "calibrating" the sensor before measuring emissive sources, the light is also not turned on, thus placing the sensor on the "white tile" exclusively is actually.. nonsense.
Because the sensor can not see the "white tile", you might as well place it on whatever and it still will measure the same (and yes i tried it).

Is there actually anything in the eye-one pro that can drift over time when using it exclusively for emmision ?
No light being used, no gelfilters inside... ?

For those that use the i1 pro professionally, how often should the i1 pro be sent back to be recalibrated (if ever)?

Greetings

Depends on the person and the amount of pounding the device takes.

My normal i1 still tracks with my CS200 after 4 years ...

I had a number of new spyder pods a few years back and I dropped one about 3 feet as i slipped. That was enough to throw the probe off 800K from then on. Probe was considered to be toast.

Regards

Because the sensor can not see the "white tile", you might as well place it on whatever and it still will measure the same (and yes i tried it).

You are correct the white tile is only needed for calibrating "Reflectance (Internal Lamp)" measurements. But it is also a good idea to use it for the dark offset calibration as well. The reason is it is designed to block all light from getting to the sensors. Since the i1Pro does not have a coupling interface to block stray light just placing it on a table or other surface you can still get stray light in. The i1Pro dark cal is very sensitive to any stray light.

Derek,

Can you just cup the palm of your hand around the sensor part of the i1Pro and get a good dark reading?
I used to be so paranoid about dark readings that I would place a large, thick black velvet cloth on the floor, put the i1 on it's cradle on the velvet, then totally wrap the velvet completely around the i1 in it's cradle. Then I went to CEDIA and saw the CF people just cupping it in the palm of their hands. I tried that and thought that the results were actually better than what I got with wrapping it in the velvet, but it could be my imagination.

Yes using your hand would work. You just need to make sure no stray light can get in.