I've got one in my '11 EC300, as well as in an '08 KTM 250xc and Husaberg FE450. I've had the Pro in the KTM and also in earlier KTMs I've owned.
I prefer the EXP as it is a 6 spring setup, and gives a consistent clutch feel (very similar to stock) for override, etc. It has all the benefits of the Rekluse, and eliminated the variable clutch feel of the Pro. It works great in all of the bikes, including the GG, and I wouldn't choose to go back to the Pro (or be without it either!)
As for adjustment, after initial install in a new bike (or after installing new friction plates), you need to run it for a short ride (approx. 20 minutes), and then re-set the gap per Rekluse instructions. The new friction plates "break in" during this short ride, and the gap has to be adjusted at that point. Once you make the initial adjustment, I have found that I don't need to adjust again quite some time. The KTM has at least 60+ hours and the berg has about the same and no adjustments required yet.
If you race or just want a "ready to go fix in the field", Rekluse recommends doing the break in procedure on a set of spare friction plates and keeping them ready for a clutch swap later so you can avoid the re-adjust process after install.