Having owned and used both polycarbonate (Ikelite) and machined aluminum (Aquatica) housings, my personal preference is for the Aquatica housings. The Ikelite housing was a bit cheaper and it did the job, but I was never fully at ease with the port system. I have seen first hand a few people with that port system end up with flooding issues - never really at depth, but when there is little to no pressure on the port (ie. on the surface or in a rinse bucket). I find the bayonette mount on the Aquatica more solid of a fit. The moisture alarm I have in the Aquatica seems to be more practical in way of moisture detection. I have had leak issues in both types of housings (both minor) and neither one of them occurred initially upon a dunk test at the surface, but quite a bit significantly into the dive itself. The last one, having a clear housing would not have helped as I do a lot of scootering and while on the trigger, it is clipped off and not in my visual sight, but I did hear the beeping of the moisture alarm in the Aquatica and was able to exit the dive safely and take care of the problem. For the Ikelite leak, I was fortunate enough to be looking at it at the time and noticed some water trickling on the dome port (which I guess I would have seen as well on any other housing) and was able to deal with the situation.
One of my big complaints with my Ikelite housing was that some of the controls would slip while trying to operate the controls at depth. I am not exactly sure why that is, though i suspect the plastic housing, not being as rigid as aluminum, would perhaps deform (even ever so minutely) so as the contact on some of the controls would be a bit off and result in some slippage. I found this to be the case with the command wheels in particular. I had actually spoken with a technician at Ikelite about this and the suggestion was to put another piece of rubber or some tape on the control to make the connection more snug. While this may work, I would not have expected this sort of patch-work solution. This has never been the case with the Aquatica housing as the controls have always been precise with no slippage.
One other thing that I found a bit irritating with the Ikelite housing I had was that the camera was mounted on the housing back, which blocked access to both the memory card slot and the battery compartment. This meant that i would have to unmount the camera from the housing back each time if i wanted to change cards or batteries.
Don't get me wrong, Ikelite makes a quality product, but for me, these are the issues that have lead me to go a different route.
As far as the cost is concerned, I think the price differential was under $1000. Is this significant? Perhaps, but is it worth it? Only you can tell for you. For me, yes.
