I was happy with the JBLs. However, sometimes, I noticed that I didn't have enough bass response. Also, I am occasionally undergunned for larger gigs.
The FBT had this great review, and it had, according to specs (and in reality as well) much better bass response. It can also churn out more watts, and it only weighs 4 lbs more.
So I thought, what the heck. Whether I can get my money back through improved client satisfaction is iffy, but this is a hobby for me as well.