Since when has Fett become some Jedi killer? And Jango Fett killed a few in Galidraan or whatever, but he's not a full-timer like Grievous or Ventress. Lastly, Boba would likely be able to take out some half-wit like Trebor, or maybe even some decent Jedi. But against a Soresu master with otherwordly dexterity and agility (think Spiderman), he'll be outclassed in a straight fight. Like Janus said, he has a chance in some situations. But otherwise, he's toast.
I'm actually rootin for Boba here. I've said it before and I'll say it again. Boba is underrated! There's no denying it (truthfully, that is). Assuming its not in a small room and Boba's jetpack is working, then I think he'll take it after a fairly decent fight. I mean, Boba's no fool and was known as the greatest bounty hunter for a reason. Skill+Experience+Environment will give him the win IMO.