I agree as a $3500 option it is pricey, however compared to some of the other stuff it's definitely a top option.
Unless you have plans to go full coilover, which really is the 'hard' option, or want a stripper on just springs -the 'cheap' option.
Handling is great on my car, however I am wondering if the variable dampers would eliminate some of the minor floatiness that is residual over larger undulations..
A car of this size definitely benefits from VDC+ARS.. which is why you only get the VDC on the 3 series.. body roll is the major issue with the 5+series.. which ARS solves with brilliance (or upgraded springs if it is not an option)
I would recommend DHP even though I don't have it.