Run them both in for a while before you decide.
You know, I kind of forgot about burn-in. I've never been a proponent, but I'm also not convinced one way or the other. How long would you say is necessary?
I've had the M80s going for about 12-14 hours' the LFRs about 8.
It's not speaker burn in, it's your reference sound burned in your brain that sets the bar for what you think/know as good sound. When you hear something different, the brain balks and asks itself "is this better? Could it even be?".
The first time anyone gets a new speaker you have a bias even though you may consciously know about it, but ultimately your reference sound starts with what you have known for a long time, the M80 sound. Take your time flipping between the two sets for a couple of weeks and try out different music as well.
Obviously one observation you have is in the apple to orange comparsion (660 vs 80). Yes the LFR880 would have been the best most equivalent unit to compare. The different driver configuration and tower size between the 60 and 80s makes a difference and so does the LFR aspect. You have TWO major variables to adjust for rather than just one.
I observed the same thing you mentioned re: the soundstage. With the LFR i noticed that the sound was more dispersed and less directional or at least less noticeably directional. The effect was more subtle than i expected and i also came to the same thought as you did; does this matter to me? or is this too subtle for me to think it makes enough of a strong positive change to make it worthwhile?
Given its price, i backed away, but if i had the LFR for an extended period to hear in comparison, it's possible i may come to a different conclusion (my listening experience happened at the Axiom factory so over a very short period of less than 1 hour).
