I don't think the civilian tanks are DOT legal, but I have never heard of anyone having a problem because of it. The tanks are said to "leach" fuel but it not something you would ever see or smell, but any stickers that you put on the tank would fall off because of it, unless they were heavy duty perforated vinyl. Mounting the tank is pretty straight forward, just be prepared to take your time doing it the first time and be ready to "solve the riddle" of the included brackets. The instructions really suck and it helps to just step back, have a sit down, and think about it for a few minutes.
The tank itself is as tough as nails and I don't think you would have any durability issues to worry about. It's probably three times tougher than the stocker, holds more fuel, and is a little lighter too. At least as compared with the same amount of fuel in each tank. There is no doubt that the IMS is heavier when full of fuel.
The only venting issue that I know of is if you have a tankbag that closes off the vent line coming out of the cap. I put a 90 degree fitting on my cap and attached the vent hose to that and have had no issues. I am running a Wolfman Explorer Light tankbag and it works very well on the IMS tank.
Hope this helps you out.