I had my mechanic fit one whilst bike was in for first major service (at 30k, ahem).
I love the bike now, so much so I've left my Z1000SX in the garage this year, despite it being more "convenient" for my touring actiities.
I think it pulls a lot better from low down, although in fairness, this is in conjunction with Super Unleaded.
It did seem to run better on the Super Unleaded before, but since the advancer was fitted, it has felt a bit rougher on the couple of normal unleaded tankfuls I've used.
A satisfied customer