I've got a 250 4x4 with a V-10 and the snowplow package, so I've got the x springs. The plow setup is approx. 1000 lbs, BTW. I had to buy the snowplow package, since I plow with my truck. That being said, the truck sits level and I like it that way. The SDs that I see without the x springs have a bit of a rake towards the front. After seeing this, I'd buy the plow package just so the truck sat level. YMMV SamC
People are installing the "X" springs to increase front ride-height. It's mostly done for appearance, but some (mostly PSD owners) have installed them to fix/prevent spring sag do to the heavy weight of the engine.