MK2 .25x700 here, and must say I am a large volume shooter @ 100 meters BR, so my observation is based on continuos 3-400 shots per week, at least, and I am keeping my ring papers - marked, for analyzing later, eventually.
I have seen a significant improvement from indexing the liner.
I have seen a significantly better groups from free floating the liner instead of bonding a CF sleeve to the liner.
I have not seen a significant improvement from my barrel (integrated) tuner, I think that has something to do with projectile frictions (sizing) when running through the liner and if the TUNE is right maybe the liner frequency oscillates less?
I have learned that the TUNE is a combination of multiple factors.
I have learned that when I am tightening the ES /SD the group size slowly tightens, but there is a brake point when suddenly opens up with flyers...
I have learned that the tightest ES/SF numbers does not give the tightest groups.
I have not tried a "latest and greatest secret sauce" barrel tensioner, but tinkering to buy one to compare the results vs barrel tuner.
My personal believe is that what is called the "barrel tensioner" actually compressing the barrel tube and not effecting the tension in liner. Tensioning the liner shall be like tensioning a guitar string... And that theory to be proven again, but we don't have it available yet.
This my opinion and not sure if helps if you hard wired
