Do I REALLY need a dually?

As a general rule, yes, you will be able to park at the grocery store! It will be much easier to park farther out where you can do a "pull through" with open spaces on either side, rather than trying to pull into that primo spot up close to the store. By no means are you excluded from parking most places. You simply have to compensate for the wider truck.

I just took my DRW truck to work yesterday. It fit everywhere I took it, no problem.

Most parking spots are plenty wide enough for the DRW, though they do vary. Use common sense and good judgement.