When we had our ride to Naracoorte a few weeks back I called into a suspension shop for prices on updating mine.
New progressive springs and oil for the front comes in at under $200 plus labour for fitting at the dealer.
The rear will cost about $730 and it's custom bulit for the bike. He asked how often I towed a trailer, how often I had a pillion and her weight. Also the weight carried in side and top cases, oh!!! and my weight. Based on my answers a progressive shock with their standard valving should be ok. $100 option to revalve if needed. In any case it would be better than a well used 14yr OEM old shock.
I asked about adjusting for preload etc when riding solo or with pillion etc. No need to adjust settings, just hop on and ride away.