Seems there has been somewhere around 126,000 1800 Gold Wings sold in the USA. Based on threads discussing the secondary master cylinder recall. Using that figure, the number of members of Gold Wing forums is relatively few with even fewer "complaining" about it's suspension.
Accessory companies are making good money from selling what they call upgrades simply by using the same philosophy used by oil companies to convince you to change oil every 3,000 miles.
Those that spend hundreds on up into the thousands are going to justify that expenditure whether or not they actually sense a "better" ride or what usually results, which is a much "stiffer" ride.
A few have been honest in their opinions stating either "no felt" difference, harsher ride or something like "I wasted my money".
I have been riding since I was 16-now 67. I have ridden and or owned most styles of motorcycles available in those years. Yes, even my sons various sport bikes!
Specifically on Gold Wings, I ride "normally" meaning I don't call myself Nicky Hayden. I have dragged my road pegs in the corners of "The Dragons Tail" but, that is a rarity.
I have not found, what I call, any significant difference in the "ride" of a Wing with suspension changes, that would cause me to spend money on any suspension change, until the time it "wears out" from mileage. Then OEM replacements are fine for me! I do make sure that rear shock is topped off with fluid!
I have now triked and even against the advice of the conversion manufacturer, I retained the OEM fork springs and found the "ride" is still fine.
In reference to the rear shock on the 1800, a gentleman far more wise than I, Tom Finch(owner of TailWind Trailers)posted an explanation of the rear suspension of the 1800 and suggested setting it on the max(25) and leave it there! I did this and my wife asked me what I have done to the bike as the "bumps" and "dips" did not seem as harsh anymore!
Tom, by the way, has far more miles on Wings(including towing his TailWind) than mere mortals, such as we will ever have. Just one opinion for consideration.
Audited to remove a statement that was an opinion only with no actual knowledge to confirm! Thank you Kando for pointing that error out to me and for editing your post.