Well, considered opinion in here is that provided you get enough copper (2.5 mm^2) then you should be OK. OFC, LC etc will not make any difference that you can hear. Now the topography of the cables *may* have an influence, i.e. this cable is separated by a web in-between, rather than your normal "side be side" lay up.
Over £45 is free delivery, so 50m works out at £1.55 per metre, which for 2.5mm^2 is a really good price no matter what the copper! That looks a great bargain to me! (Clearly-AV have it for £2.95 per metre!).
Speaker cable is cable. There is apparently some poor quality copper cable for sale on Ebay, but generally the purity of cable from known sources is pretty good. Given decent copper, the only significant difference in cables is their size.
The poster on your link mentions later in the thread that he has bi-wired his speakers with 4mm^2 cable - 8mm^2 in total.
If there is any real improvement over his previous set up, it is likely driven by the additional conductor CSA rather than the 'linear crystal oxygen free copper'.
UP-LCOFC 2 x 2.5mm, shotgun, PVC/neoprene jacket
I dont believe you will hear a difference between any of the cables installed in your system the Blue Series is the most flexible of the bunch so far easier to install in any Consumer system, the Black Series has a stiffer jacket and the LCOFC being shotgun is stiff in one direction and not ideal for getting around bends etc.