I ordered my DX early last year, received it just before winter, and the accessories that I ordered with it did not show up till winter. Given that they sat all winter, and I just got them on last weekend.
center stand (still has not arrived)
I got the aux tank, for one because sometimes you need range, second the price would only go up for this option, and it is highly unlikely there would be an aftermarket solution.
Well, I got all the accessories on and a few things I've learned. Taking the main tank off is not a huge deal and you have to do it to do 90% of things on/to the bike. I suggest leaving the fairings in place if you don't need to remove them for access. The bottom fairing bolt's rubber bushing really needs to be two pieces, next time I have them off they will be cut in two. And, the main point of the post, is the fact the rear tank is extremely easy to remove/install. We are talking 7 bolts in all, with all being easy access. Six 10mm bolts hold on the tank and you have to remove the exhaust hanger bracket as well.
To remove the aux tank, remove the seven bolts, cap off the two fuel lines and secure (or remove) the wiring. Then reinstall the correct exhaust hanger (you have two now). Maybe 30 minutes worth of work.
My plan is to only have the aux tank on when going on long journeys. I'm going to run a little while to see if the new lines grow on me but as of now I much prefer the clean rear look. I've ordered the prerun moto rear rack (which can be used with the tank) and Adventure Spec side racks, signed up for notification when they start to offer them, so I'll have two different configurations for the bike, side racks for my Mosko moto reckless systems (for a slim look) and the aux tank, which also works with the reckless system. She really looks like a hefty girl with the tank and bags on 'er.
I'll be happy to answer any questions about the install. Not a lot of info out there on the aux tank and real-world usage.