[MN2///M]

I do not have this option, but have towed around 5500 lbs a few times behind my 35i. The standard suspension works fine for short trips and/or lighter loads, but if I was routinely towing >4000 lbs, I would have definitely opted for the upgraded suspension. $1500 is a small price to pay for the added safety.

Reliability should not be an issue for many years. Air suspension tends to be a problem once the airbags and other components get old. Even then, catastrophic failure without some warning is very unlikely in my opinion.

For what it is worth, those that have DHP swear they will never buy another without it; what's another $3k?