Hi mfalco,
There are a few recent threads running that I hope you have seen. I'm in southern Maine just up the road from you. I was certified in June of 05. I've made 76 dives so far in New England lakes and ocean waters so I think I can speak pretty directly to what you should be considering.
First, set the 3mm asside. Save it for travel, a nice skin-dive on a pond or even a shallow July August fresh water dive above the thermocline. It's a very liberating experince as New England diving goes. We actually did one evening dive in swimwear this past July!
Second. I have never owned a hyperstretch suit. Other brands make similar high stretch suit. It's not hard to find a body of owners who say they don't hold up as well. The same is true about not being as warm. The flexibility that allows for the stretch and comfort allows crushing and loss of insulation at depth. Some swear by their Hyper-stretch suits, there is no free lunch.
Now onto what I suggest.... Since you have set asside winter diving lets go down the wetsuit road.
The common suit for ocean diving around here is a 7mm suit with a second 7mm layer for the torso & groin areas. This can take 2 principal forms.
1 A John and Jacket. This a set of wetsuit pants that also covers the chest and has shoulder straps. Added to this is a step-in jacket that starts mid thigh and covers the torso and arms. It's probably the most common configuration historically.
2. A fullsuit and a hooded step-in vest. This is what I dive and I like the fact that the full suit starts as complete membrane covering me. The hooded step-iin vest gives me the second 7mm layer for my groin and torso. The hood is integrated with the vest and effectively eliminates the neck as a source of infiltration. The vest also mutes any zipper seepage into the suit. The bare vest includes gasket seals in the arm openings to minimize flushing between the 2 layers. I dove this configuration in perfect comfort down to 50F for back to back dives before going dry for the winter. In the warmest nonths I swap the 7mm vest for a 3/5 mm chicken vest worn under the full suit. This keeps me comfortable and lets me leave 4 pounds of weight in the gear locker. I even use a 5mm suit and beabie for some fresh water dives. In your case starting out you need to dress for the coldest first.
There are some other threads here and in the New England forum about getting the most out of wetsuit diving. In short most divers can enjoy diving wet from sometime in May and into November without much trouble. The limiting factor is often not the water temperature but rather the end of dive changeout from the wetsuit in open air at the divesite, especially at the November end of the season. I have had very good luck with Bare products.
That's my story and I'm sticking to it.
Pete
