Skiing the Pioneer is quite similar to the Alaska XP... But very different than the Alfa Free! The main differences are the flex and the feeeeling...
The forward flex (Flex zone #2 in the picture) is on the softer side on the Pioneer and Alaska XP. Which makes striding very smooth for nice and effortless transitions while XC skiing, but it also makes it easier to put pressure on the BOF in the traditional way. The Free is super stiff and much harder to flex in the same zone, which will give some skiers a better sense of safety, stability and control. On the Free, it's easier to use the cuff to flex the bellows, something you can't do on any other boot.
The feeling is totally different too. The presence of the Pioneer is almost non-existent. As I said, the feeling is the closest to being barefoot. Super-freaking-light, a feeling like if you were hovercrafting on snow. In the very same way of the Alaska XP, I think it's simply the best feeling ever for a XCD boot in my opinion. On the other hand, the Alfa Free feels like having your feet stuck in a cast. (Well, a super comfortable and superlight, adjustable cast!) A feeling of being more "anchored" in the boot, which can also be desirable depending on what you are looking for.
If you appreciate the pure telemark essence, the reward of the Pioneer (And the Alaska XP) is just unbelievable. If your priority is a sense of security instead of feeling, and the telemark turn in itself is not your main thing, the Free will make you feel in control of every situation like never before... But yep, at the expense of some feeling points... That's the thing about rigid boots... They give a more alpine-boot feeling rather than a pure telemark feeling...
Now about the flexors, both boots are getting a few bonus points on the downhill using the hard ones. But I have to admit that personally, I am not that crazy about the new XP hard flexors... More on this in a separate post...