I spoke at length with the head mechanic at the Honda shop who installed my monotubes. He said he had installed hundreds of monotubes and only one guy was so dissatisfied that he changed those forks back to stock. He said he could do the same for me, if I wish. He says he follows the instructions furnished by the manufacturer and knew there was a difference in the amount of oil in the forks. He repeated what Progressive told me by phone that the springs in the cartridges are stiffer than Honda OEM. We talked about the ADV and Jr. said mine was working properly. When I got home I removed the top of the ADV anyway, tested it (it works every time I depress the brake pedal) and took a ride but did not see a vast improvement. I started to just bolt it back together but then decided to do the "hole in a nickel" thing. Still, no vast improvement in riding comfort. Progressive said they would send me a return authorization and I could send the monotubes in for testing, but since I have only 26K miles and I am not an aggressive rider (you can read that as an old slow fart) I may just go back to the stock set up, which I have. I could probably sell the monotubes for a reduced price and they would be great for a heavy person or someone who likes to push the limits of a Goldwing. One more thing. Progressive said removing the pre-load spacers would soften the spring bounce some but their monotubes were designed to be stiffer than OEM. Alternatively, I can ride the dang thing and try to get used to a rougher ride.
The mechanic puts the spacers in, based on his experience and analysis of how big the rider is. If I had known they make a BIG difference, I would have asked him to leave the spacers out. OTOH, from what the Progressive tech rep told me, removal of the spacers "may soften the ride some" but he could not quantify how much is "some." I'm beginning to accept the philosophy that Progressive cartridges (with or without spacers) are for aggressive riders who scrape pegs every now and then, or for support of two up weight or a heavier rider than me. A Goldwing is not supposed to feel like you are riding on a donkey.
I did a lot of reading before I went to PMT's in 2013. Back then, Progressive's instructions were to definitely put in at least one of the spacers they supply. There was a lot of discussion around whether the spacers were really needed for an 'average' size person or not. I spoke to Buckskin about it because I was also installing a billet tree at the same time and he advised/convinced me that I wouldn't need spacers, and I didn't put any in. The improvement in the ride was very noticeable. No more harsh shock in the handlebars from hitting bumps and holes in the road, no more twisting from road snakes etc. And I promise you, I am NOT an aggressive rider.
In 2015 my PMT's failed - they locked up pretty solid. Holding the front brake I could only compress the forks one inch and then bang - no more movement. I reinstalled the stock setup and sent the PMT's to Progressive for testing. It was interesting going back to stock. Much much softer feeling, but too soft, and all the stock handling characteristics were back. Not a BAD ride, but not as nice as with the PMT's. Progressive replaced my cartridges and I put them in when I got the new ones. Now, the instructions say not to put in any spacers unless you feel you need more preload (i.e. a heavier than 'average' rider). Even when I spoke to them on the phone there seemed to be some confusion among the employees whether spacers were needed, but as I said the instructions now say they're not needed in most cases.
Anyway, if you can compress your forks more than an inch holding the front brake, you don't have the lockup failure I had. My guess is that if you remove the spacers you'll enjoy the feel, but yes, if you have to pay to have it done it'll be pricey. Do you think if you showed the new PMT instructions to your mechanic he might give you a break on the cost of removing the spacer since it basically says he shouldn't be putting them in in most cases?
FWIW, the old original instructions said:
"Put one of the supplied “C” shaped preload spacers between the top of the fork spring and the upper spring seat. Do this on both Monotone assemblies."
The new instructions say:
"Though we feel no extra preload spacers on each cartridge assembly is optimum in most cases, you may feel you need more preload. If so, do not add more than one of the supplied preload spacers to each fork."