BUY IT !! You will be glad you did. I had a seal go out on my 05 Ultra just after the factory warranty expired, extended warranty paid over $500 ......50 cent seal $499.00 labor, cost me $50.00 !!
Now I always get the extended warranty if I plan to keep the bike over the 2 year factory warranty period. Trust me it is worth every cent, you won't be sorry !! However, I did not get the warranty on my 08 Ultra SE3 did not plan on keeping it over 2 years, well.... 26 months later..... it cost me over $3500 for a crank replacement. You can get a refund on any unused portion of the warranty if you sell your bike early.
Also, as far as mods are concerned my previous 2005 ULTRA had a power commander, V&H pipes, tru duals, oil pressure gauge, after marker chain tensioner, 255 cams.....and several other mods. Dealer just repaired the leak with nothing said, they did not seem to care. Don't believe some of the BS on this site, consult a reputable Harley dealer with your questions, get it in writing on the extended warranty contract what they will repair with your mods, most Harley mods are covered.
I never do the tire and wheel warranty, only the mechanical 5 year warranty, matter of personal preference.
Make sure it is the Harley warranty from Harley or from the Dealer , there are a lot of worthless warranty's out there. The Harley ESP warranty goes by the bile SN when you take it in for repair, no hassle everything is in the Harley computer, including the Harley mods.
My .02 worth from previous experience.