Sadly I had a lapse in judgement and owned an E320 cabriolet for a year.

I would hardly call a E320 cabriolet a lapse in judgement :D

+1 here

I have never owned a gasser Mercedes and don't see any point to that.

You would have the disadvantages of more expensive tune-up parts like the Distributor Cap and have to have Smog Tests done on the Car.

And, there is the Computer to deal with.

If you are going to have a Gasser go Japanese or American. Get the same performance at less initial cost and lower maint. costs.