Looking at the regular service intervals in my '06 touring owners manual I see nothing special regarding the 20000 mile service.I know yours is not a touring model (Ithink),but what could be so different?
I already did the 5,10,15,20,25 and about to do the 30 on mine.

The answer to your question all depends on if you trust your work/ability.

 

And the other question, do you have a decent set of tools. Of course one or two services done at home will pay for a darn nice starter kit!

 

I'm not handy with tools anymore, and these bikes are too expensive and too technical for a moron like me to mess with it. That's why I bought the dealer's three year full maintenance package. I expect that they will do all the right things, and my experience with Zion HD is that they will. Plus, the tech that works on my bike is the same one everytime, and factory certified and trained. Lot of bang for the buck in my mind.