IMHO, the size of the sails is a factor as much as the size of the boat. Our 50 footer does not have the tall mast, which I believe makes her easier to sail solo. I believe the poster with the ketch is seeing a similar effect with managable sails even though the boat is big.
We don't have any electric winches or in mast furling. Rather, we have a stackpack with lazy jacks. With nice size manual winches, sail handling is easy enough. I don't think I'd want to sail solo without the lazy jacks. And the stack pack means a simple zip-up protects the sail from UV.
We have an electric autopilot. If we were to do long distance cruising we'd want to have spare parts for it.
We have 4 kids, the oldest is now 6'3". The room on our 50 is good to have. I don't have to worry about storage or weight. We've had empty storage spots. (I finally put beer in one of them.) Our tankage lets us go for weeks without refilling our water tanks. We can hold a bigger battery bank and have more solar panels too. So there's no rationing of electricity.
As an electrical engineer, the electrical systems come easily to me. So it was a natural progression to add an inverter for the microwave, stanchion lights, long range wifi and other things. I read-up on refrigeration systems and with some advice from Cleave at SeaFrost, I put in our electrical refrigeration/freezer. Yes, I do much of the work. I thoroughly enjoy it. Maybe because I have a desk job, but it gets me outside and gets me some exercise.
Haven't done any passages yet, but the bigger boat makes for a different experience in the weather I've seen. What was described as a rough day by someone on a Catalina 37, was a beautiful day sail on our boat. On one trip from Block Island to Montauk, we actually played Parcheesi in the cockpit while motor sailing along with a lowered traveller. None of the little game peices fell over. And with some competitive kids, it was a raucously good time.
All of the above is to say that I like the size of our boat, can (and often do) sail solo, and don't feel any desire to go smaller.
Not sure about a bigger boat, since it would likely mean fewer day sails. Perhaps we all are comfortable with what we have and see bigger as meaning less sailing. It would be nice to have a raised saloon, that raised area midships that bigger boats have. You know, where you can eat breakfast inside and look out over the anchorage, or stand at the helm inside. If we ever got a bigger boat, that would probably be what led me to get it.
When soloing, I think the time it takes to get to the bow is a factor, for when anchoring, docking, or grabbing a mooring. If you are quick on your feet, you'll get "up there" quicker and you'll be more comfortable with a bigger-sized boat.
The Ketch is a much easier rig to an equivalent area cutter rigged sloop. I can drag around and hank on every sail on my 65' ketch that I couldn't on my 57 sloop. But ketches perform better on the wind the closer they get to an equal masted schooner and with some separation between the mainsail clew and the mizzen tack.
I wonder how many people who are scared of the idea of a large boat would change their opinion if they actually experienced the benefits ? I changed my view decades ago just after one 5 day passage on a 70 footer, compared with my 40 footer at the time it was bliss.
Since then I have had 45' then 57' then 45' again and now 65'
A lot of people are scared of boats that they are unable to manhandle, but larger boats you just adopt different techniques. I find there isnít much difference between my the 45 footer or the 65 footer except you canít just push the 65 off a dockside if the wind is pressing you on, then you need to know how to spring the bow out or use a bow thruster if fitted.
Iím just taking my large thruster out as we just donít use it and Iím shedding weight ( both entrained water and the weight of the gear) and gaining a bit of buoyancy by reclaiming the tunnel. So I apparently don't have a problem handling the boat. I see people thrashing the water with bow thrusters and still coming to grief when a little seamanship would have made life so easy !
Handling the boat shore-side just takes a bit more thought and you proceed with care and a bit of planning itís more small ship handling than small boat handling. But if you keep your speed down the engine stops you just as promptly as with a small boat (providing you have a decent prop installation).
At sea in heavy weather the big boat is easier to work sails, the decks are much more stable, drier and moving around is easier as you can keep your feet. Spreading the sail area over two or more masts is very sensible. I was never happy with my 57 foot sloop It was anxiety inducing in heavy weather. Iím Very happy with the ketch rig on a 65 footer and I would never go back to a large sloop rigged boat now. Light air sails are also fun on a ketch.
I really like the mizzen staysail and Iíve seen equal masted staysail schooners with 3 masts that were quite easy to sail.
Also I think lazyjacks are mandatory offshore. I donít like going offshore without lazyjacks in a boat over 40 feet unless it has a furling main.