The only reason I haven't changed out mine is that your too limited with respect to tire rotation. When you go this route you have to break them down to rotate, due to the reverse offset.
I am able to get all six into the rotation without having to break them down.
Mac
Ah, the price of vanity..... but I know where I can use a tire machine really cheap... .
As far as the fuel savings, they are minimal. To break even, you basically have to run the wheels for the life of the truck as the first owner... ... depending on who you are, that's gonna average around 200k. On a class 8 truck, average life is around 500-700k, first owner, so the wheels pay for themselves a little quicker, and when you add the weight reduction on 8 wheels, it helps with payload capacity, tire life, and overall performance of the truck..... How much you tow, how you drive, and the price of fuel all add up to payback. Personally, I like the appearance, as well as performance, so it pays me back a little quicker.....
As for the Dodge Aluminum wheels, my personal opinion(for as little as it's worth) is they are JUNK! Scrap Iron. Guano. Bantha Pudu.
Tire size is pretty limited. If you go to the 265s, you only gain a small amount(only in certain brands, some brands are shorter by . 20 inches), but the cost is minimal, as well. If you go to 315s, the cost is pretty extensive, as you'll have to go with a spacer for clearance. That's a PITA..... not that I don't do it...

For the torque my truck makes, the 35s are about right with 3. 73 gears..... but then there's the fender extensions, speedometer corrections, mudflaps(depending on your state), and eventually, you like it so much you want another one..... it's a very nasty cycle... :--)