I looked real hard at a Dive Caddy II. I know there's a III but all that's been on their website is "coming soon" and a link to a trade show demo video. So based on that - my observations:
First let's factor in the recent announcement that the airlines are wanting to reduce the size of a legal carry-on. No matter what Chuck Shumer and the others postulate, there's not going to be an act of Congress to keep that from happening. Only by 1/2" L/D though. So probably still OK. But they also want to reduce the width a full 2 inches - from 9" to 7". I wonder how that affects the compressibility of the Dive Caddy if that happens. You can only squeeze so much in a bag.
An issue I've always had with a Dive Caddy is my preferred fins are 26" long. Which means I always check a bag. In the video Chad mentions that his demo fins are shorter and then shows how you can use the fin compression straps to bend yours and make them shorter. But he doesn't actually show it. Simple common sense tells me that in a 9" space I can't bend my fin tips 4" down to 22" unless I fold them completely over. Also my fins have hard side channels that extend near the end, no way a compression strap is bending them that much. A solution is the Aeris Accel Travel Fins - they're under 21".
But they'll also fit in a $30 conventional carry-on as well so save the $$ on the Dive Caddy, buy a roll-up travel BCD like a Covert or a Zuma and still have room for all your other gear etc. And a few clothes. I also travel with video gear - no way that's going in a soft-sided bag that could be gate checked.
IMO Dive Caddy only works IMO because the gate attendants haven't been paying attention. Or people don't fill it full.
At least initially, if they make the carry-on size reduction, they'll start to pay more attention. 3 things are driving that - First most people (myself included) are going to try to sneak our 1/2" oversized $200 carry-on on the plane. And the airlines know this so I predict a lot more showing that your bag fits in the sizing box pre-boarding now. Second, the cynic in me wouldn't be at all surprised to see a "oversized carry-on fee" payable at the gate implemented for those that don't. Third, some of the airlines are squeezing even more seats onto the plane than would seem possible. That's all happening in coach...LOL. So more competition for the already limited overhead bins leads to more gate checking on full flights - which there's more of as all the airlines merge.
If you watch the video Chad mentions that in the event of a gate check you remove the turtle pack and repack your shorter dive caddy in their provided duffel bag. So that begs the question - has it always been oversized with the turtle pack attached? I'm pretty sure we both know the answer...
I've been gate-checked 3 times. One I knew about - small prop-jet connection. Once it worked the way it should, tendered my bag at the gate, saw it go downstairs and recovered it at the gate at my destination. The third time it was supposed to but on arrival in Houston all the gate checked bags were fed into the baggage conveyor system and I recovered my gate-checked bag on the baggage carousel. Watched for it so that someone else's bag didn't smash into it as it dropped onto the carousel since my $3500 worth of video gear was in it.
So that's why I don't think I'll ever get a Dive Caddy. YMMV.
I haven't looked at the Jetpack enough to comment on it. For me for a week of diving it wouldn't work. For a long weekend it probably does. fyi in the photo ontheir website showing all the gear you can pack in it - the fins are the Accel Travel Fins. One other thing to check is availability. LeisurePro is sold out, the only other sites listed in Google Shopping where they're in stock are Coral Edge in VA or eBay. Makes me wonder if they're discontinuing them during the Aeris integration into Oceanic. Or a rebranded Oceanic model is on the way.
hth,