Ah ha! Yes i had mine done.
Give the guys at West Coast a call. They tend to buy in bulk from Oz so you may have to wait a while if out of stock.
Cant remember the exact price but it was £600ish mark. (foam cell, kit B) They dont charge much for fitting and its a fixed price so if it all goes wrong its no worries for you. With mine, they had an absolute nightmare getting the front shocks off and there was much swearing and hitting of things. IIRC the fitting was £150, i am more than capable of doing the job myself but for that money the charge just to send it to me would have been £50-£70 so i worked in a business trip at the same time and did it all in one. You only need a wrong bush etc and the truck stays on stands on the driveway for a week.
It might be worth talking to them anyway with the problems you have, they are friendly and more than willing to help out. Worth asking to speak to Paul as he is the boss.
With regards the suspension itself? There is much debate over all the types but i am more than happy with it, had the same on my 80 and its all about reliability for me, i know the AHC can be reliable, but my main reason for the 100 is an upgrade from the 80 and will get used for long loaded trips so simplicity is key.
If you want to have a go in mine just let me know, i work overseas so time is limited but if you can get to West Coast they normally have one sitting around you can try.
Let me know if you have any questions. HTH.
EDIT: you may be able to sell off some AHC components to offest the cost of the Ironman.