There is so much missing and outright wrong information on this platform, it's not surprising you couldn't find the details you wanted. I've spent (wasted?) countless hours reading and researching about it.I wish the sales guy would have better explained it to me. I did research, but all the information on it was pointing to it needing to be charged daily. I tried looking for information on it and not allot was told on the recharge or regen systems. Well, maybe my next one will be the 4XE as I really did like it at the time, but the diesel one out at the time.
You can absolutely drive it without ever charging, just treating it like a hybrid. It seems that folks have been getting pretty good mileage (~26MPG) in stock configuration with the battery indicating 1%. The advantage here is that it will still use the electric drive when at lower speeds and acceleration levels even when "fully discharged".
Charging daily will definitely yield the best "mileage" and save money assuming your driving habits and electricity costs are average. The purchase price is actually less than a comparably equipped model if you can take advantage of the $7500 tax credit. Ordering early, I was forced to buy the body colored top & fenders and I still saved about $2k over getting a regular gas model.
Imjester77, your diesel is likely to be a long lived, torquey powerplant without many reliability issues. The 4xe longevity and reliability is unknown. It should be great, but I expect teething problems for the first year, and hope it lasts at least as long as the battery warranty (10 years).