Personally, I'd go with the 610 which includes:
1. Samsung's incredible CMS system to get colors almost perfect with calibration
2. Samsung's new 10pt grey scale system
3. I think you also get streaming and other connection stuff.
The only reason to get the C5000 series is if (like me), you think need a thin set due to space issues.
I've got the UN32C5000 and am thinking of changing to a standard LCD. The edge lighting on my 5000 is starting to really bother me with dark scenes (can see the "lights" at each corner), and this set doesn't do a great job with primary and secondary colors at all.
Black levels are great though.