Rainin' on my parade again. LOL!
I can't argue against the bags and did seriously consider them. I would still consider them in the future. Back to the springs, TTC-1223v springs are shorter than OEM once installed and ultimately still result in too low of rear end on MY truck when towing, even after adding 1" spacers. TTC-1223 and TTC-1211 I think are pretty much the same, but the 1223 are taller. The ride is stiffer, but not harsh by any means. I've ridden in half tons with bags that were harsher. One major advantage I see is the simplicity of the springs. No air pressure to check, virtually no chance of component failure.
Happy Camping!