From the SeaPiper website:
"Strength and structure: The hull bottom is solid hand laid fiberglass that is mostly 1/2in (12mm) in laminate thickness below the waterline, and 3/8in (10mm) laminate thickness above the waterline which is cored with the superior Airex coring material. This hull structure is extremely strong, well insulated, and the Airex cored topsides offer superior stiffness and impact resistance. The structure is reinforced with strong 2-inch thick Nidacore sub floors and EIGHT very substantial transverse bulkheads, five of which are designed as watertight bulkheads. Longitudinally there are two full height bulkheads under the sole from the stern forward that offer tremendous additional stiffness to the structure."
I get the fact that you are not a fan of the SeaPiper and that's fine, but the above paragraph defines the definition of sturdy in my opinion. The SeaPiper website has tons of detail on the specifications and construction details of this vessel. All vendor supplied equipment (hatches, vents, lighting, etc.) is identified by model number or part number. I have been tracking the birth of Hull #1 for the past 18 months and the company has been very forthcoming about sharing information and answering my many questions.
As for capable, I think a rock solid by reputation Beta engine coupled with a SeaKeeper 2 gyro and 270 gallons of fuel makes for a pretty potent combination. As Hull #1 was just delivered last week in California, I obviously have not seen one yet, but I am hoping to do so later this year. I will admit to a certain bias towards practical, workmanlike looking boats. The Great Harbour N37 falls into that category and the SeaPiper has always reminded me of a Navy launch.
Boating is all about choices, for a little over $200K you can buy a new 27' Ranger Tug with a 300 HP horse gas outboard or a 35' SeaPiper with a SeaKeeper gyro and an 85 HP diesel inboard. I know what I would pick.