I think
Chris while we may have some slightly different views of the speakers but I think that we are both very much on the same page as to how good they are.
I like the words microscopic view of the mix. I have use the term feeding your mix into a small bottleneck too that creates this microscopic view.
I find it amazing that on such a small limited range speaker at such low volume so much information can be gleaned from it. It is a secret weapon in my view. I love it and spend way more hours on the small speaker than my main speakers by far. Yes I check things up there for sure. I tend to start the mix on my mains and get it 80% right and then switch over.
It is great also for things like kick and bass. If they suddenly go very low on the small speaker it means they need more mids and high range harmonics to still keep them audible. It means there is too much low end thump in those things which you only tend to hear on larger systems. It is a must for balancing vocals over music. Something many get wrong. People tend to have vocals way too loud. When you get this right on the small speaker they will sound perfect up loud on a big system as well.
I think the driver needs to be able to handle a little bit of power. I have got a 4" driver in a small box but it is rated at something like 35 watts though. Also I have got a decent power amp driving it too. (several hundred watts) I think that helps. Of course I keep that way down low but it is nice to have the headroom in the poweramp as well. You don't want it struggling or farting due to low end etc..Mine has actually got a tiny tweeter built in as well with a crossover but I have put a wirewound pot in series with the tweeter and have it off most times.
I find once things sound very balanced in this speaker, mixes just instantly translate perfectly to everything else including my car as well.