I see from you sig that you currently have a TDI, and you own a DMAX.
While I personally don't have any experience with a gasser T3, I can tell you that the towing experience with the gasser is going to be radically different than you're used to with your T2.
The turbo on your T2 is the great equalizer. It doesn't know or care what elevation at you're at. It's pumping air into the cylinders all the time, and that makes the vehicle think that it's at the same elevation all the time. That's an overgeneralization, but it's a good analogy.
While the gasser will "try" to compensate for that with fuel injection, it simply cannot compensate for the lack of air, like the turbo does.
Be ready for less power higher up, and be ready for a screaming engine all the time. If you pull with either your T2 or DMAX, you probably already know that the engine doesn't really "rev" until it's really being worked hard. Expect the gasser to be revving A LOT MORE, and expect it to be revving when the diesel would not be. The gasser will work harder, and sound like it's working harder...