I have Celestion A1's, which are bi-wireable. They come with golden shiny straps. I used a variant of the wire I am using to make jumpers, I didn't really hear the difference. (I am not saying that you wouldn't) So then I used true bi-wire, and this did indeed make a difference, a better one for me. Note that I say better for me, this is all subjective. Then I purchased another amp (on my way to active crossovers) and used one amp for bass and the other for the highs, and that really made a difference, but that had much to do with the amps.
One other thought, and if someone can weigh in on this I would appreciate it too. I have been toying the thought of getting the cable you have for bass and then getting the Oval 12 for my highs. The one thing that I did learn in trying different size of cables, at least for my system and speakers, a larger cable (9 gauge) for the highs sounded worse then the 12 gauge I ended up using. So the thought is, Oval 9's for the bass and Oval 12's for the highs. This may be more affordable and perhaps the best solution.
Remember, you never know until you try it. I understand your dilemma not being able to try something from USA prior to purchase. But you can get most of your money back in the resale market if you purchase wisely. Good luck and let us know what you find.