While we were out hiking the other day, we passed a guy that was wearing a weighted vest. He was kind enough to stop and talk to me about it for a minute.
He had one of the 40lb Xvests. He didn't think the plate loaded one was a good idea, as the plates are much wider than the cylindrical weights on the xvest. This was something that I hadn't thought of. It would probably seem pretty rigid having those plates strapped on to you.
He also mentioned that he wouldn't ever feel the need to go over 40 lbs. I'm not sure what to think of this though. He seemed smaller than me, I'd guess him to be around 170lbs or so, maybe 5'8. So 40lbs is almost 25% of his bodyweight. I'd need 55 lbs to reach 25% of my bodyweight.
At the moment, I'm leaning towards the 75lb v-max long vest. It seems like the better deal price wise compared to the xvest (though it's still $270

). I'll be using it primarily for hiking/walking and some BW exercises. So I don't think I would need to get the short vest, which appears to be more geared towards fast-paced activites where you need a full ROM.