No, I haven't yet. I did send a pair of the Mark IIs and an original set to Alex for his review on the Entity 1.1 in Stereophile that is linked in the Entity section, although he didn't mention the different versions. While he found some things he liked about the MkII versions he felt the originals were more musical and engaging. Unfortunately testing them isn't as simple a task as you might think. Why? Due to the lack of perfection that was just mentioned in another thread here. While most people, and most of the industry for certain, would rather ignore it the fact is that there are no two products that are absolutely identical. My two SMs do sound slightly different, as I'm sure do my two TMs and my two SINGularity units. (I say "I'm sure" as I haven't actually compared left and right SINGularity nor TM, nor do I want to as that way leads to an even deeper psychosis!) ;-)
Every cable will sound slightly different, or sometimes not so slightly, as Fredrik mentioned quite some time ago. I have at least 7 pair of original Linn Silvers. which I have listened to and paired and marked with numbers to keep track of which are paired. (One particular cable is audibly better than any of the others with another one a close second so they make up pair 1 despite their differences - there goes that psychosis again. Life would be much simpler if it was all still mono!) Pair 1 goes from SINGularities to SMs, pair 2 went from SMs to TMs, pair 3 went from Kremlin to SMs - I was obviously optimizing the LP12 signal path. With the Källa I have to currently use a longer pair of cables to reach the SM on the far side of the racks. But if that changes it will likely get pair 2 and pair 3 will go SMs to TMs.
I think you can imagine the nature of the dilemma. If I compare any random pair of MkII Silvers to my originals do I get a fair picture of the actual difference? Probably not. So I bought 3 pair of Silver MkIIs and I have burned them all in. But one of those pair is still with a reviewer along with the Entity 1.1 and pair #3 of the originals. Once I get those back I can take some time and listen to each MkII cable and pair them up in order of most musical quality. Then I can compare the best of the MkII to the best two or three pair of the originals to see if they are any better. I also think I still have a pair of the Mk1s but with the newer style RCAs (which we already know aren't as musical as the originals) that I should throw into the mix. It's so nice how simple these tasks are. Still nowhere near comparing 380 different firmware parameters!
What is the difference in the MkII? I couldn't figure out anything from the looks of the cable. There is also MkII of the Black interconnect wire and they look the same to me as well. So I asked a contact at Linn and was told that the original Black and Silver wires were made for Linn in China and the MkII versions are made locally about 20 miles down the road in Scotland. Silver was changed over in 2019 and Balanced Silver and Black were changed in 2020.