Having used both a Zephyr vest and an Exovest, I can speak to both. I started out on a Zephyr vest, and now own an Exovest. They are both very different styles, and one is not better than the other - it's simply what works best for you. If you're able to try both out before making a purchase decision, that would benefit you greatly. All the videos Chris shared are brilliant for Exovest explanations. The biggest differences I found between the two vests were (and keep in mind this is me, not everyone):
- My stamina increased in the Exovest due to the torque being higher up on my back and distributing the weight of the rig differently across my body.
- (This is true for everyone) I walk differently in the Exovest, as Chris explains very well in this video. Summarized - you must let your pelvic bones rise and fall in an Exovest so the vest is working with you, not against you. In a normal vest, you must hold your pelvis level.
- I can breathe diaphragmatically (versus accessory breathing, which is not wise in any vest - shallow breathing where your shoulders rise and fall, which can cause all sorts of neck and shoulder problems etc.) much easier in the Exovest, as it does not sit on my lungs whatsoever. I also very much like that it doesn't sit on any organs (no feeling your sandwich right after lunch!) or your spine.
- The Exovest is very unforgiving if you are out of form; you want the sled on your centerline, or else you'll feel the vest "collapsing" in one direction due to the weight of the sled pulling too much against the pivot points. Personally I see this as a good thing, because you want to be in good form anyway! On the Zephyr vest, it's easier to get away with being out of form, though because there are no cross-back straps, I found this was easy to feel in that vest as well.
Again, try both and see what works for you!