No. I would buy the .biz and redirect to your .com. I have NEVER seen a .biz in search engine results. I dont even think Ive ever visited a .biz domain.
.COM is Commercial which is Business. There is no real need to use the .BIZ alternative if you already have the .COM. The .COM is probably more popular and thus deem to be more valuable. Going from .com to .biz is like downgrading your status. However, there is no harm is getting the .biz in conjunction with the .com to prevent someone else from registering a similiar name. I guess I would only got to the .biz if I badly need the name and cannot find it in the .com space.
I just wanted to shorten the url to two words because i have "business" inside domain. I'll stick with a 3words domain name then thanks guys