From Todd Brown (pakman94) in the Edmund's Forum:
I have both a '00 ML430 and a '00 X5 (non-sport) so I can easily tell you the differences between the vehicles. The X5 (one over month old) is a replacement for our '99 RX300.
After spending significant amounts of time in each vehicle, I think that I've to agree with "aling1" on many of his points. In the X5, there's a tighter feeling than in the ML, as if the cockpit is wrapped a little more around you. This is, of course, true as the X5 has significantly less space than the ML. It gives the illusion of being in a sportier vehicle. We bought the X5 because we didn't need the utility of the ML (although a larger cargo hold would've been nice) and were originally considering the E430 4-matic sedan. Luxury-wise, the X5 is a little bit better in this area than the ML430, but I expected it after paying more than $10000CAD over the ML430.
When we have to haul adult passengers at the back though, the X5 is not as suitable because the rear legroom is not really very spacious. This is something that you should keep in mind if you occasionally transport people.
Safetywise, I have to say that both vehicles are comparable to each other. The ML430 has standard rear side impact airbags, and the X5 doesn't. Of course, the X5 has the head protection system for the front passengers. The only situation where this system really helps is if for some reason you are struck by an object from the side, such as a pole. Other than that, it wasn't really much of an issue for us. SUVs as a class are safer than cars in side impact crashes anyway and both the ML430 and X5 (I'm guessing here) are best in class.
As far as handling in slippery conditions go, I think that this goes to my ML430 hands down. The X5's all-season performance biased Bridgestone tires are simply not as good as the Dunlop Grandtreks on the ML. Additionally, I've found from experience that the X5 is rather tail happy because of its 32%/68% power split. Although the DSC helps to control the fishtailing, it is rather disconcerting (and annoying) when the system keeps cutting in. The M-class 48/52 power split is much more neutral and easier to control. When the white stuff falls, I keep the X5 in the garage. The skidplate and brushguard fitted on our ML430 also gives me more confidence when plowing through the deep sections of snow. Handling in dry conditions is a tie, I think. Both drive very well, although the X5 has a touch less body lean. Because the X5 rides firmer (hence less body lean) than the ML430 and so it is not as comfortable on rough stretches of pavement. I prefer the arrange of the Steptronic gearshift (up/down) over the MB Touchshift (side to side).
The ML430's braking also seems to be a touch better than the X5's. I think that this primarily has to do with the fact that the X5 carries around 300 pounds more bulk and has slightly smaller brake rotors. Overall though, both vehicles are excellent in this area. By the way, I have never found the ML430's wipers to be a problem and I was extremely surprised to read that you thought that their placement was a joke. Are you playing around with the seat controls? One quibble that I have with the X5's wiper controls is that if the vehicle is left with the switch on, it has to be turned off and back on again for the wipers to function.
One option that I would've skipped in the X5 is the GPS system. Although it is a nice toy to play around with (I'm a gadget guy), it doesn't have as much coverage as I expected and is complicated to use. I also don't like the fact that this only leaves me with a tape deck. Who uses tapes nowadays anymore?
I've also noticed that the X5 uses more fuel than the ML430. Not a whole lot more, but I get about 2-3 mpg less on average than the ML430. Again, I attribute this to the extra weight that has to be lugged around and I hope that it will improve as the engine breaks in more.
Reliability-wise, I have to say that my ML430 is more reliable to date. I have had zero problems with it so far (it is 4 months old). In contrast, I've had to go back to my BMW dealership for a steering column recall inspection, a defective seal on the right front headlamp that allowed moisture to buildup inside, a rear hatch that was extremely difficult to close, and finally rear tailamps that wouldn't go off (some type of electrical problem because of the rear hatch). This goes to show you that whenever possible, one should probably avoid buying vehicles in their first model year.