Everybody likes to hate on Parkers, but comparing one to a DE is really apples to oranges. The DE is going to be bigger, just on that fact alone it will be more comfortable. Also you are comparing two radically different hull designs, planning vs. displacement. Plus two very different cruising speeds. They both have their merits.
I have a 25 Parker Deep Vee, it suits me well. I enjoy going 35+kts when I have the opportunity, and can also cruise fairly economical if needed. I can pull the boat on its trailer with my truck and I can trim the outboard up to get into shallow water. My dock is on a tidal river so that means a lot to my situation.
A DE is going to be slower and more solid in rough water, plus more economical because of the slow speed and single engine. A bigger boat is always nicer too.
That being said I bet a lot of guys who own downeast boats once had a Parker, its a natural progression. I say go for it. But as Steve said be careful. Do we really want to be out there in less than desirable conditions? I know I don't need to be. Commercial application is a different story.