5" woofers will sound anaemic in the bottom end though JBLs are voiced to be pleasing rather than neutral and neutral is the aim for mixing.
I've been researching for a monitor upgrade and in the 7 - 8" woofer range there're some contenders...the ADAMS TV7s are good value & sound the TV8s are even better for AUS$200 a pair extra. The Yamaha 8s are nice, the JBLs 8s are, to my ears, voiced/hyped a little in the mids and are popular as speakers for TVs and book shelf sound systems. There're a lot out there and the prices are reasobnable - yet the quality of sound is quite good even at the prices.
Be cautious about front ported monitors as they can cause a narrow cancellation effect.


Cheers
rayc
"What's so funny about peace, love & understanding?" - N.Lowe