I've been looking at some of these systems as an option for my new BCD. You call them "integrated" inflators, but there are quite a few systems out there. If I'm not mistaken these are the main systems and their differences:
Mares Airtrim and Seac Sub Air Control:
These systems are alike, since they both use pneumatic valves. Inflation and dumping is done using two buttons on the BCD. The dump button connects to two dump valve (top and bottom) through a pneumatic system. Some (older) Mares bcd's only have one top valve, which makes dumping when inverted more difficult. The downside of pneumatic valves, as mentioned, is that they don't work in an out of air situation. First of all you shouldn't get yourself in this situation, but if you do, you can still dump air using a normal pull-cord dump valve on the right shoulder. So rest asured, dumping is always possible.
Cressi Flight Control System:
Like Mares and Seac Sub, Cressi uses two buttons for inflation and dumping. The difference is that the dump button is not connected to a pneumatic valve, but to a normal valve, using a steel wire. The dump button therefor works in any situation. The downside is that the system is only connected to one valve on the left shoulder, so dumping when inverted is more difficult. Another downside of the Cressi system is that the buttons are not attached directly to the bcd, but they stick out a little. Seems to me like it can easily drag through the sand or get stuck behind something, but that's just my 2cents.
Scubapro, SeaQuest and other systems:
If i'm not mistaken all other system than the Mares, Seac sub and Cressi systems, that get rid of the corrogated hose are basically the same: Inflation is done with a button on the BCD, like a dry-suit inflation button (actually, some are litteraly standard dry-suit buttons). Dumping however is not done with a button on the bcd, but with the normal pull-cord valves located at the normal places. The system works in every situation, but the downside is you have different locations to pull when you're in different positions. However, some (or maybe a lot of) people already use the pull-cord valves instead of having to hold the corrugated hose up, so nothing changes for them, except the bulky inflator is replaced by a sleak button.
So, as i see it:
- if you want to get rid of the inflator and be able to inflate and dump in any position without having to look for the right button/cord: Use Mares of Seac Sub
- if you don't trust the pneumatic system, and don't mind dumping being more difficult when inverted: Use Cressi
- If you never use the corrugated hose for dumping anyway and you don't mind using normal pull-cords: use one of the other systems
- If you don't trust any of these systems: stick with a corrugated hose. But keep an open mind, these systems aren't invented for nothing. I read a lot of comments about these systems not working perfectly in every position, safety issues etc. from people who haven't tried them or know anyone that has, but just make assumptions. I haven't read many negative comments from people that actually tried them, most are quite enthousiastic.
Just my opinion, don't have all the answers