I have found the Flashback cables to be at least as good/if not better than standard Naim stuff.
I haven't tried the AR Lunar, but my order of preference is
AR Skylink--more relaxed, smoother, yet more detail than the AR Yellow
AR Yellow--Excellent upgrade over the Naim Lavender, similar in quality to Hi-Line
Flashback cables (though not tried the Premier range)
Naim Lavender.
I never really heard a Hi-Line for an extended home demo, only in other peoples systems (very similar to mine as was) & in Shop demo's.
On that basis, it seemed to offer nothing that the AR stuff does at more sensible prices, + it doesn't fall apart every time you touch it!
OK, thats a bit flippant, but the build quality is distinctly un-Naimlike.
Essentially, if I need a lead replacing, I go to Flashback, as I think they offer great products & service at sensible prices.
If I want to "splash out" on something a wee bit more special, then I go for AR leads.
Matt.