I used their horn relay harness kit several years back on the R65LS - I could have wired something up myself but wanted to see what they provided and do a test run for some other friends. The kit was good, and arrived in a very surprisingly short amount of time, considering they are based in Japan. Maybe they have a distribution point in CA of something, but it only took a few days to show up - and shipping costs were reasonable, too.
IF one doesn't have the ability or time to search out proper wiring, connectors, and relay(s) at local parts stores, it is definitely worth using their product, IMO.