YES I did, and
Absolutely YES
You are correct on the diameters or OE sway bars, and of the Hellwig upgrade bars. They come with very solid poly bushings for the end links. This makes for even more roll resistance and you will feel how much more solidly your coach sits on the campsite. Few upgrades help both moving and parked.
Our E450 had those same small sizes. Yours uses same upgrade sizes but with different attachments. Your new bar will attach to the pads with surface rust on the 2012 axle in this pic, just
click on it. I had already bought Hellwig bars for our E450 when it still had the 2002 axle, so you can see the U-bolts Hellwig used for that axle. Yours will look very OEM, just bigger.
This reply may draw some very technical-sounding rebuttals, but I can tell you there is NOT a downside to stiffening an RV this way. Daytona, Indy, Sebring, sure. Not on an RV. Works just fine. You'll like it.