It really depends.
There were several production generations of the 6000, and quality didn't match on all. Same for the 3000 and 4000. The biggest issue appears to be that some units were tweaked for PAL (even if marked "NTSC" with the green sticker), and the NTSC had noise in the signal. It can be a great TBC, but also might not.
Trivia: NTSC/PAL is an undocumented change on the motherboard via jumpers or DIP.
Like the DVKs, it's actually a chroma keyer with TBC. But the 6000 TBC is more similar to the 1000 than the pitiful 5000 inside the DVKs.
The 1000, by contrast, tends to be more uniform across the production generations. You do sometimes see 1000s with vertical bar patterning, and slight softness (slight chroma offset?), but not as often, and it's really more unit-to-unit than a sub-model problem. The 3/4/6000 is definitely a model line issue.
Just FYI, the CDM-1500 that I have available is almost identical to the TBC-1000 performance.
Here:
http://www.digitalfaq.com/forum/mark...bc-1000-a.html
All TBCs add some degree of processing noise, and the goal is to get one with good transparency (zero to minimal noise). Some entire lines of TBC are unacceptable for this reason (Big Voodoo is a good example, all BV should be avoided, horrid image noise is added). While others are production runs or generations. And some are just individual units.
If you don't know for sure, realize you're gambling. And if you're a video newbie/novice, you may get a bad unit, and not know any better until it's too late to return it.
