Just my two cents..........
I have had my 2013 LX570 for about a little over a year now. So far I only used the LX570 to tow our open utility trailer (single axle 12 ft x 12 ft.) for back yard landscaping projects such as the landscaping red bricks for the edge of the sidewalk. One time we loaded up with the trailer 200 of these and did not feel a thing........ of course these are "light" in comparison to the others above.
Before the LX570 we had a 2000 LX470 (when we traded in it had like 280K miles and still running strong on original engine and transmission). A few years before we traded in, I used it to tow a flatbed Uhaul trailer with a MB SLK55 AMG on it. We went cross country from middle of USA to SoCal home. Went through some small mountains and yes, I can feel the trailer. I also knew we were at its maximum, if not already exceeded it by a good margin. I had towed a lot of stuff with that old LX470 since we bought it new, so I knew how to do it and what to expect.......longer merging time on the on ramp and takes longer to stop and all that......... PLUS the need to anticipate other vehicles move in front of me just in case if someone decides to cut in front of me and etc.... One thing I noticed on the old LX470 is that the gas mileage decreased dramatically to like 5 miles per gallon on mountain passes!!!!
I usually change the engine oil BEFORE and AFTER a cross country towing like that and the transmission fluid when it is due.
With LX570, I don't think there will be any problems.......