Here's a February '08 comparison review from Tom's Hardware.
It doesn't include the OCZ Vendetta 2, and I'm not sure if it includes any of the other "Direct Touch" coolers.
Tom's Hardware CPU Cooler Charts 2008 Part 1
I've been away from this for awhile, so I'd need to see whether there is a "Part 2."
If you read the hype at ThermalRight's website on the Ultra 120 Extreme and other coolers, they tout the nickel-plating with the justification that it prevents corrosion and "protects" the pipes. But we never remove the nickel from the pipes themselves -- we only sand off the nickel on the base.
The nickel degrades performance slightly (because the metal has a higher thermal resistance than copper). So the question then arises in the mind of ThermalRight devotees such as myself, if the "Direct Touch" heatpipe models are "weaker" in construction, or whether any such weakness really matters much.
Since I'd made some experiments with a silver-dollar that I destroyed to see if a silver shim would improve cooling, anyone would draw the conclusion from such an experiment that any added thermal interface, including the commonly-used flat heatsink base, reduces effectiveness. So why didn't the manufacturers develop "direct-touch" earlier?
And what might the effect be for filling in the "cracks" at the base of the "direct-touch" models with nano-diamond thermal paste?