Installer, installer, installer. I found a 1st class, "Mom and Pop" type shop 20 minutes from my house, then asked whose kits he sold. In my case it was Motor Trike.
After a deal was struck, I paid about 1/2 up front to order the kit, already painted and color matched. Two weeks later the MT Phoenix IRS kit showed up delivered from Texas to NJ. Dealer called me to drop off the bike and promised a one week delivery. Five days later he called me to come and pick it up... Except for the 1000 mile check, have not been back for trike service since. (I've been back but not for trike issues).
Others may have a different thought, but in my opinion all the major kits have pluses and minuses. If you do have a problem, I don't want to be "400 miles" (or whatever) from my dealer.