Nice truck, they sure have come a long way from my 1999 Superduty dually. Mine had a measly 4000 ish lbs of payload before my family got in the truck...what kind of payload capacity do you have on your door sticker?
As far as a dually being more stable... Than a SRW...well, it's got 100% more tire contact in the back...that's double the sidewall's and twice the contact patch on the ground...plus it's got a wider footprint..physics says it's more stable....a wider base is more stable than a narrower base with a similar load.
Thanks!
Jeremiah