Well just to put my opinion in, I spent over a year with a beautiful used Thumb NT 5 from eBay and I loved it. Then I picked up a Thumb BO 5 from an acquaintance at one of my gigs and I truly fell in love. He couldn't get me to put it down.
I don't have enough money to have more than 1 expensive bass, so the first thing I did that weekend after I sobered up was put my Thumb NT 5 on eBay. Of course, it sold in no time (I got $1700 for it, paid $1300, so that was a nice bonus).
Then I bought a 2005, mint condition Thumb BO for $1200. (By the way, don't you LOVE those people who spend ungodly money on a bass and never play it? Let's us almost poor folk take it off their hands cheap. I mean, the gold lettering is still perfect and I have never seen that on a 2 year old used Warwick!)
So my point is, don't believe the NT hype. Believe your ear, not your wallet. If NT is the way to go, great! But for me, I could dial in a much brighter, crisper mid-range cut through than I ever could on my NT 5.
Maybe it was user error, but the NT 5 was always way more subdued. I found it a very reluctant bass, if you don't mind the personification. I had to really hammer on it to coax out the growling metal-mid thump that the BO gives me with a wink and a smile. That girl really loves me (or maybe she just loves me for my amp and pedal).