The Korean TRBs are very good basses and an excellent value, especially if you can score the 1006 in the sub-$750 range.
As has been mentioned, the electronics are probably the weakest point. First of all, more than one reviewer has found that they eat batteries. I haven't kept close track, but playing about 5 hours a week, the Duracell 9v I put in most recently has lasted about 5 months and is about due for a change. As a conservative estimate I would think you'd get about 200 hours out of a battery. Sounds like a lot, but compare this to some other preamps that can get 600hrs or more out of one cell and you see it's a bit inefficient. Also, if you turn the panpot off-center you start getting single-coil noise. At least on the fiver, this is due to the assymetrical coils in each soapbar (they're dual-coil humbucking, but one coil is larger for three strings, and the other one smaller for the other two). I generally don't turn the panpot past 90* from center for this reason. With the panpot centered, the bass is very quiet. A sixer may not have this issue at all, or it may truly be an issue with the electronics.
I find the EQ very easy to use; I have my amp set with a slight notch at 625Hz, and a slight boost to the low and high mids, and from that I can tweak the bass EQ or the seperate bass/treble shelving controls on the amp to get a large range of sounds.
The necks on these basses are very thick, but still feel natural; it's a flattened C shape that feels like they took a four-string neck, cut it in half lengthwise and put a spacer in the middle. It's not exactly like that, but you get the idea. The edge of the neck is very regular, making the upper frets feel very similar to the lower ones. That thicker profile coupled with the 35" scale give you a killer B-string. It's very well-defined, and in standard tuning is very firm and playable.
