Methinks there is more to 1/2 ton vs _____. The gear ratio variable is the wild card with motor size a close 2nd.
My 2005 F150 (5.4L, 4x4 Lariat Supercab and with all the options, 144.5" wheel base) with 3.73 gear ratio has rating (with stabilizer bars) of:
GCWR: 15000 lbs
Max trailer towing: 9300 lbs
The F250/F350 version (5.4L, 4x4, Supercab, 144.5 wheel base with 3.73 gearing)
GCWR: 16000 lbs (1k bonus to F150)
Max trailer towing: 9200 lbs (100 lbs less than F150)
BTW, Ford says the F250 numbers are within a 100 lbs of the F350.
Now, if we change the F250/F350 gear ratio to 4.1, it is a different game.
GCWR: 18000 lbs (3k bonus to F150)
Max trailer towing: 10700 lbs (1400 lb bonus to F150)
And (drum roll please) jumping to from 5.4L to 6.8L engine is where the big jump pops up, the towing capacity increases to 13,600 lbs and 15,100 lbs respectively.
LOL, who would have thought the trailer towing capacity would be 100 lbs less for the F250/F350, when compared to identical engine and gear ratio of my F150.
That's why I purchased an F150 over the F250/F350 to tow my Nash 20' TT (GVWR 7000 lbs)...and it is a joy to drive sans my Nash TT.