I would rate the difficulty of the install as a 2 or 3. It took me maybe 4 hours and would have taken less time except the first compressor didn't have the right bracket on it for the 09's. I ended up straightening out and re-bending the bracket so it fit in the space properly only to have the compressor be defective as soon as I tested it. The 2nd compressor had the correct bracket and slipped into place easily and has worked perfectly.
If you have any mechanical and wiring knowledge you will be able to figure everything out fairly easily to install the Arnott Aldan air shocks. I have not worked on my own bikes in the past and I have performed almost all of the work on my 09' SERG since day 1. The only 2 things that I did not do myself was install the chrome inner primary and replace the handlebars. While the dealership was installing the handlebars, they found out that the hydraulic clutch cable was about 1/2" short even after re-routing the cable. Since there was not a exact (cable color) match for the hydraulic clutch cable, I am having both the hydraulic clutch cable and brake cable replaced so the color of the cables is an exact match. I would not have been able to perform the work associated with the ABS brakes, replacing the brake cable and replacing the hydraulic clutch so I am glad that I took it to the dealership for these 2 projects.
Sorry, I got off the subject a bit. The job of installing the Alden air shocks yourself is not difficult. and there is a sense of accomplishment that I get when I do the work myself. Also, if you don't already own a motorcycle service lift I recommend that you purchase one as it will make the job of taking the shocks off and installing the new ones simple. The motorcycle service lift (jack) comes in handy for working on your bike and many other uses including washing the bike, polishing chrome and cleaning the wheels.