I'm coming up on 500 lifetime dives, mostly on a Zeagle (standard back inflate, now my travel BC) and TransPac (harness and donut wing)... a few, since last year, with a new Hollis SMS100 (I've gotten into side-mount), and about 40 on the Dimension i3 (my local diving grab and go fun rig).
My biggest issue is with those that make critical judgments on the i3 without ever having donned one, much less dove with it, simply because it's not conventional. After ~40 dives with the Dimension i3, I can say, in *my* humble opinion, that this is the most kick-ass, absolute fun rig I've ever used...
My experience has been that the trim is spot on, and I've heard this from a number of Dimension users -- perhaps due to the Wrapture harness which is also responsible for making it the, without exception, *most* comfortable rig I've ever worn as per supporting the weight of the tank. This may not be an issue to many, but those of us that do quite a bit of shore diving, and hauling, and may not be as young as we want to admit to, it's manna from heaven.
As for the i3 system itself, the mutli-blow function means I don't have to care what orientation I'm in, or think about which dump to pull. I'm not concerned about where the air bubble is parked, as with my side-mount rig, so I prefer all the vents blowing at once... And, I've found MUCH LESS water, at times NONE in the bladder, after multiple dives, than with my conventional rigs. I'm not sure if the mutli-blow valves also operate as check valves which would explain this, however, it just happens to be the case.
The lever sits right where my hand naturally falls to when I bring it to my side, and micro adjustments are a piece of cake. I've never (so far) had a leak, a stuck inflator, or a failure of any nature. The corrugated hose is familiar... but, that certainly doesn't make it better... just longer in the tooth, with admittedly more wring out time (which *doesn't* mean you don't have free flows on integrated octos, stuck inflators, and port separations with the "tried and true" corrugated rig).
Finally... the thing is an absolute gas to dive (no pun intended). It's well thought out, comfortable, so far extremely reliable, and, for me, a keeper. I agree it's a fun rig... and meant for simple, recreational depth excursions -- which last time I checked made up the overriding majority of most diving...
If I had to give it any d-merits, there would be just two changes I'd make: add a 2nd cam band (I've never had a tank slip, but I simply prefer two bands); sell the medium size on up with a choice of 30 or 50lb. lift bladders. I prefer a smaller wing, and don't like the extra heft and size the 50 adds. Neither of those points are deal killers for me, considering how much I enjoy this rig, when I do the types of diving I mentioned...
So, if some of you want to beat it up, be my guest... but at least beat it up from a position of informed and experienced perspective, rather than just blowing your own valves...