I have my rear fogs, but I just bought the switch. It is useful in heavy storms, or when someone is on my ass and i want them to back off, but I wouldn't run them all the time.
I HATE it when people leave them on the entire time. It is very annoying, so I am happy bmw didnt include it for the average consumer, as most mercedes drivers dont care and blind you the entire time they are driving...
Current 07 BSM E92 335i
Previous SGM E90 330i (R.I.P.)