I had one with my ST170, there was a difference, it seemed to pick up quicker but the annoying stutter at 2000rpm was still there (a ST170 Trait) i eventually went for Dreamscience and it got rid of the stutter and felt stronger, unfortunately you can only get a one shot remap from dreamscience now the handsets are not avaliable unless you find one second hand.
The increased rev limit you get with a remap is good though, with my mods it did help me hit 60 in the 6's
Bluefin will realistically gain you 5-6bhp on the ST170 i ran mine on race 4 setting super unleaded and it did sub 20mpg allot of the time