I purchased this block, Performance PCs is still selling them even though Swiftech isn't. They hardly seem to carry half of their products for that matter, u have to go to third parties for anything to be in stock!
This was a really good review though I don't think that flow resistance really brings down this block like the performance calculation indicates. If you have a good pump it is not an issue.
I decided to go parallel with just one gpu block and I am very happy with this blocks perfomannce. Even getting 1/3 of the flow it is great. The high thermal performance makes it work well even in low flow loops. The microfins actually balances things out vs the gpublock's higher flow.
With the parallel loop, the 1.95 SKF resistance and the .76 or so in my Phanteks 1080 Ti block (estimate based on Techpowerup reviews of 1080 and 1080 Ti blocks), that comes out to .55 total resistance for both in parallel, borrowing electrical parallel circuit maths (same principal).
Anyways I think the block is underated in the weighted performance calculation since resistance wont matter a whole lot to enthusiast build performance with lots of rads and pump power.