Will I hear differences between 8TC and 12TC?

Can I expect to hear differences between Kimber Kable 8TC and 12TC speaker cables if I am using relatively small, efficient bookshelf speakers?

B&W DM602 S3's, to be exact.

And if I compared 8TC and 12TC in single, internally biwired runs?

I currently have an 8 foot pair of internally biwired 8TC speaker cables, which I like the sound of, but my final curiosity is if I'd hear improvements in the 12TC, especially because my 8TC is internally biwired, ie only half is powering the woofer / midrange.
There is a popular belief that thicker more robust cable, such as the dedicated subwoofer cables transmit bass better. There is a chance that the dielectric and shielding also affect the sound. Given just those two considerations you may hear a difference . Whether you like it or not is completely subjective.
Can you expect to? hard to say. All depends on your setup, your ears, and your general ability to hear very small differences.
The main thing to expect to find would be slightly better bass presentation.

If you took your 8TC and changed it to be 6 wires for the bass ,and 2 for the treble..
When I used 8TC biwired for my B&W 805S speakers i actually used 8TC with 14 of the 16 wires for the bass, and only ONE PAIR of wires of the set for the treble. Worked GREAT.

Considering the bass uses ten times plus the power that a tweeter uses..
AB comparing cables i guess is substantially easier than speakers.
Both are great choices and just the right one will do the trick.
If you didn't see, I gave you an answer but it was on your other thread. I didn't see this one until after I posted.
The difference between 8TC and 12TC is extremely small, if even detectable.
I sold a lot of Kimber in the past. These days I seldom sell it. Because Audioquest is a big step further. They need to improve there cables. They still make nice cables, but often you can get better ones for the money. It also depends about your speakers and length if te 12TC will be better.
Bo1972, which Audioquests do you find to be in a similar price range but worth considering over the white/clear 8TCs?
I have had the 8tc. Currently have the 12tc. I changed because I needed longer length cable, 15', to reconfigure my system otherwise I would have put my audio $$$ elsewhere. At shorter lengths, the cost differential between the 8 and 12 tc would probably not be justified. If you like the sound of the 8tc keep them.
Tonyp, For me Kimber turned out to be the ONLY cable that actually makes sense and really works. Other brands using excessive reactive parameters to deliberately change the signal so consumer "feels differences". Kimber is the most newtral cable you can ever think of. Other brands, including AudioQuest in the simimlar price range will not perform as good and as newtral.
Rocket 33, better sound, better blacks and better timing.
I like Audioquest better, as well. Why not also consider a good used pair of CV-6 or CV-8? They have a better grade of copper and DBS than the 33.

I still say, though, that you already have pretty good cables and the money may be better spent elsewhere in your system.
I sold a lot of Kimber since a long time. I still sell it. But in comparison to many new Audioquest cables they do not match this level. The stage of the Audioquest is wider and deeper. The individual focus of instruments is sharper. There is more drive and also more detail. I personally do not agree with your arguments.