I'd lump adjustable, folding and gull-wing ladders right down there
where you have rope ladders--barely serviceable. The j-hook or friction
designs can also give you a thrill unless the hook end is very wide
compared to the rungs. And then the standoff tubes have to be long
enough so the ladder stays in contact with the hull in a gentle roll.
You'll probably have to make some compromise here if you plan to use the
same ladder over the transom. Check out www.westmarine.com to get an
idea what's available, then take your specs to any decent welding shop
for a custom ladder at half the price.
Regards,
boatdreams