polycarbonate is probably the hardest material to print with I've yet come across. Even the guys at polymaker who gave me the pc plus - can't tell me how to print it lol
The sheet of buildtak they gave me - did stick to the pc, permamently. I mentioned this to them and they said: yes that happens. And it's shrinkage makes abs look positively stable.

You will need not only a high temp all metal hotend but a sealed heated building chamber and some kind of magic print surface that even the people who make the filament can't advise on.

todd - I said use pet-g, personally I like pla - but if it doesn't work in salt water - then use pet-g.

fred - whether or not a 3d printed part is water tight is largely down to the way it's printed. Anything that isn't watertight can be painted with varnish, or any of the propriatary 3d print smoothing compounds around.
pet-g has much better layer bonding than abs, prints on an unenclosed machine and isn't much more expensive than abs. It also has a lot less shrinkage, which helps reduce micro gaps in the structure.

The fumes from abs are not as much of the problem as it's shrinkage and all the acetone you end up breathing in.
Yes people use it, I suspect many of them do so beacuse they haven't bothered to look seriously at the alternatives. The materials advances in 3d printing filaments in the last few years is just astonishing.

Another material you might want to look at is ninjatek's Armadillo. It's a rigid supertough material, that apparently prints easily. Handling it you'd think you were holding some kind of hardened nylon. I believe they said it was polyurethane.
Pretty impressive stuff.
I haven't tried it yet - but had along talk to the ninjatek guys and handled a few prints. The only thing that impressed me more this year materials wise, was a fibreglass composite from an italian company (maybe spanish). That was as light and strong as traditional fibreglass and printed - again - on an unenclosed machine.

Then you have innofil's new Pro 1 - easily the best material I've printed with for ease of use.
Lots of different applications depending on how hot and how fast you print it. Also food contact safe.

Like i said, I did spend 6 months exclusively using abs - it will teach you an awful lot about how to calibrate your printer and how not to get frustrated when yet another print fails. But as an end use material I was never impressed, and it's just been left way behind by the new guys on the block.