Well, the last time I moved from NC to CA I just shipped the X because I just didn't want to deal with having a trailor again... but the time before that (NC to CA and back to NC about 11 months later) I did all the same research you are doing and everyone kept telling me that just because you have the X in neutral, there are still moving parts that heat up and your tranny cooler won't be running so while it's ok for short'ish trips, TX to SC is a bit much. The first time I moved U-Haul wouldn't even rent me a dolly because of the weight and the top heavy-ness (word?) of the X. I ended up buying a flatbed car hauler for around $1400.00 new and did it that way, there and back. Was quite the pain and pulls you all over the road. The X is a heavy beast and aerodynamic as a shed... especially when passing or getting passed by big rigs! GEEZ!!! Like I said, this time I shipped the X and the Titan for just over $1300.00 coast to coast. You should be able to find a shipper for about $00 or $500 plus tax (just guessing, maybe cheaper) probably a little more $ than renting the dolly but there is a pain in the ass factor that is worth it's weight in gold.

Hope that helps