Let’s walk through the drawings
Headsails- Walter Schultz/Shannon thought to optimize center of effort in stiff breezes with that placement. Now coastal in light air broad reaching or running every time you want to gybe you need to roll the genny entirely in and then out. Two person job. Slow and you need to plan ahead.
Hoyt boom. A total PIA. Sure self tacking but you’re going to want the jib anytime there’s a decent breeze. Particularly upwind. You just can’t get a nice flat sail with the cord in the right place with that set up. Going need to go forward and tie more spaghetti in if you want to hove too.
Forward cabin looks poorly ventilated. That plus all the salon glass means either a dark boat with shades down or the AC running all the time.
Full keels mean a lot of wetted surface and drag. Mpg ain’t going to great. Full keels means a lot of skill and prior thought when tight quarter handling. With the distance between prop and rudder even more difficult. Pointing will suck. Do they publish a sailing polar? If so take a close look and compare to other sailboats that cost and size.
The aft cockpit and companionway cause concern. Seems scupper dependent for drainage and quite large. Add in modest freeboard I’m concerned about a boarding aft quartering sea or a pooping. Now you also have a wet exhaust. Depending on how it was done could cause big problems. How high is the loop for the wet exhaust? Will those double doors hold up or do you get significant down flooding? What happens when green water fills that big aft cockpit? What and how is all that salon glass installed?
Now try to image the sight lines. Think you’re going to be going bow in everywhere.
So without a walkthrough looks like an expensive coastal boat that’s neither fish nor fowl and probably EU B. But even if A not something I’d trust in a seaway.
True Knowlege is the Product of Direct Experience.
I recognise little of what you state above and have owned hull #14 for six years, covering well in excess of 10,000 NM's.
It aint a sail boat, it is a Motorsailer! A compromise, and a good one from owning and using one.
Bob Johnsons concept was to keep owners of Island Packets buying the brand when they got older and were looking towards a Trawler.
The self tacking hoyt boom has distinct advantages. It acts as a vang with a free sheet and its inherent friction allows easy goosewinging downwind without a pole.
The standard Lewmar 40 powered winch makes sail handling easy for a mature sailor/sailors.
The two dorade vents are direct into the owners stateroom, the one you say is poorly ventilated. It also has three opening portlights with optional bugscreens.
The boat has no genoa. It has the Jib on the Hoyt Boom.
There is the option of a 165% lightweight reacher on a Solent rig with a powered furler.
As ALL Solent rigs, this must be furled to Tack or Gybe.
Surely not the drama you suggest with a powered furler?
I have just retro fitted such a system on our boat, outhaul, trim and furling controlled by the OE Lewmar 40 powered winch Starboard side, manual Lewmar 45 Evo winch Port side.
This should give significant increase in light wind sailing ability, almost doubling the modest SA/D.
Fuel consumption at a sail assisted 2200 RPM is 3.5 litres per hour, not heavy by any measure. Our passage average speed taken over 10,000 NM's is 6.5 KTS. With the main up and pinned in tight going upwind the motion is rematkably seakindly in comparison to 12 metre motorboats.
One of the first hulls - #11 IIRC - almost made the NW Passage. The skipper was a retired Royal Marine, used to taking orders. When the authorities suggested he turn back, he did so. Three other vessels pretended they had not heard and successfully carried on.
I suggest a vessel capable of such a voyage is not as unsuitable as you suggest!
We have had very large following seas, never yet had water in the rear cockpit.
We have been on some pretty rough stuff too - Tom Cunliffe once said if you can sail in the English Channel you will be able to sail antwhere.
I think he is right.
All boats are a compromise.
The Island Packet SP Cruiser most certainly is. But a far better compromise than you suggest - without you having sailed on one!