2 runs of KK 8TC or 1 8TC and 1 4TC

They'll definitely sound different, but only you can judge if they're better. But if you plan to do a double biwire, I would definitely use the exact same cable for both runs, and not mix them.

I had the same speakers with a Pass Labs Aleph 3 amp. I used Zu Audio LIBTEC speaker cables, single run with Zu Ibis jumpers and they sounded great. If your budget allows, I would go with the ZU Event speaker cables, single run with jumpers, I have never heard a worthwhile improvement by bi-wireing.

I don't know which configuration would be better, or to use 12TC and jumpers. I wanted to post a response just to say that I have found the Hyper Pure copper used in the TC cables to be grain free. I use it throughout my system. I think it's a great bargain.

The 12TC has slightly better extension - I'd say a slightly fuller sound, but the 8TC on one of my systems works fine.

If it were me I'd just do the 12TC I think.

As for jumpers, I make my own using two pieces of Kimber TCX wire (same Hyper Pure copper) and Kimber Postmasters.

How long a run do you need for you speaker cables, by the way?