If jacks were lower cost, we would have gotten them back in 2007. At the time we figured we would add them later if we changed our mind. That was 12 years ago and we still don't have them. At times I really wished we had leveling jacks. At other times I am glad we don't. We always have a tow vehicle which helps a lot for limiting the inconvenience in handling Lynx Leveler ramps.
As mentioned by biglegmax, with model 2351D you have to closely watch your rear axle axle-over-load, even considering the rig rests on an E450 chassis. The rear-axle weight transfer is dramatic on our E350-2350. I suspect something similar might exist with model 2351D.
As far as movement of the rig when parked,
CLICK HERE.
There is one thing to keep in-mind about leveling. If you often "go primitive", the parking pads are also primitive, sloped, and uneven. For uneven conditions, I often am successful in moving the rig around into and out of low spots to level without the need for ramps. The bubble levels by the driver works great for that.
Whether using leveling jacks or ramps, you can adjust a maximum of around 4". I have seen class-A's adjusted "level" so much that their front tires are off the ground. I don't think class C jacks are safe to use in that way. People here will correct me if I am wrong. Whatever the limits are, be sure to understand them.
I am not bashing jacks or trying to talk you out of them. They sure seem great to have for typical conditions. If your budget is accommodating, it's not a hard decision.