APW 2607 is correct in noting that SRS (Self-leveling Rear Suspension) is packaged with the 3rd row seat option. There are two down-sides to 3rd row seat. First, parents of munchkins will want you to haul their brats around. Second, selecting it means you cannot get a factory (donut) spare, so you are pretty much stuck with RFT's for the life of the vehicle.
The fact that your Senior Client Advisor did not know this is troubling - it's been that way since the E70 was introduced in MY 2007.
You note the difference in MSRP between the JGC and the X5, which I guess is relevant if you are paying cash, but even then, only in the short run. I would expect the resale / residual on the Jeep to be pretty abyssmal, and for the leasing deals to be pretty unattractive. No data points on this, but a pretty strong hunch. Similarly, if you are financing, I would think the trade-in value of the two brands would be vastly different 3 years down the road.
Don't forget that 4 years of maintenance is included in the X5's price. We had 3 JGC's and, while the parts prices and labor rates were relatively low, the Jeeps spent a LOT of time in the shop for brakes, wheel bearings and the likes. I'm on my 6th BMW (3rd X5) and I don't think I've ever paid a dime in repair costs. Life is good.
Finally, the thing that drove me away from Jeep (first to an XC-90, then to X5's) was the photos of rollovers and fatalities, the most famous being Seymour Cray, inventor of the Cray Supercomputer. In way too may cases, the A Pillar / windshield support collapsed like spaghetti, all the way back to the B Pillar, with predictably fatal head trauma. (I find it troubling that you can find almost anything on Google, but the photos of Cray's crashed Jeep have all disappeared.....)
Statistically the odds of a fatal rollover are probably pretty low, but I did not want to risk it with my wife or kids. (The engineering may be better now, but those photos left an indelible impression). If you Google "X5 Crash Photos" I think you will be awed by the integrity of the passenger compartment (like this 100 mph crash one, where: "Driver walked away without a scratch"):
http://www.wreckedexotics.com/x5/x5_20071003_001.shtml