A few more...
Speaking of "improvements" that we have made in the last decade...
(and I will skip over some upgrades to existing equipment due to age or wear)
I would put Ventilation at the head of a crowded list. I added two Beckson ventilators to the cabin top, and added a total of seven ventilators to the lower part of lockers and settee fronts throughout the boat interior. I was motivated because one of the reasons we got a deal on the boat was that it was a veritable mold farm throughout all the hidden spaces inside, and getting that pervasive smell out was a high priority. We succeeded, but it took several years.
Also right up there would be the autopilot I installed right after we got the boat -- an Autohelm ("Raymarine" nowadays) A4000S that we still use every time we go out.
Another change that really helps us get underway quicker was replacing the stack of teak hatch boards with one lightweight composite panel -- it stores flat against a bulkhead in our head compartment. Those old boards were 3/4 inch thick and were potential missiles every time we tacked, not to mention all the time spent inserting and removing the whole lot of 'em.
Other little changes that made the interior more livable early at night was a flourescent light fixture over the galley, and for late at night...
an accumultor into the pressure water system.
Refrigeration might be worth a mention, too. There was a breaker and label on the panel for it, because it was once a factory option. I installed a Frigoboat "keelcooler" system and we just love being able to come down and go for a sail with cold pop/water/ beer in the fridge!
Of course, one cannot mention the fridge without mentioning the increased house battery bank size-- with two golf cart batteries we can easily go two days at anchor without running the diesel.
Opinion: Ericson Yachts, iMHO, built a quality boat, i.e. a "good foundation" on which to make improvements like this. I have been aboard a lot of other boats in the last 30 years, some lots nicer and some a lot cheaper... and it's just not worth my time on earth to put labor and $$ into "gold plating a cowpie" !
my .02 worth,
Loren