Some great additions at the end...
Am equally intrigued by the KJ Miller "Junior Engineer" engines, both in terms of their variated setup, as well as their unique heating system.
Have a couple of the KJ Miller compressors here as well...or 3 in fact.
Started by purchasing a 110V version, just because they were from the same manufacturer as the Junior Engineer.
Upon its arrival, i noticed that the compressor itself, could be removed and used as a standalone accessory, to be driven by a steam engine, so had to import another for that.
Just a few months later, i discovered that KJ Miller in fact exported these to Europe as well back in the day, so my OCD naturally forced me to bag one with a 220V motor too, just have the collection "completed".
As far as Saito engines goes, i find that the brand generally is in a league of their own, and that the V4 demonstrates that more than most of them.
They´re just exquisite pieces of mechanical machinery, and the Tribute replica shown here as well is definitely no less in that regard.
Thanks for bringing these treats to your table as well Daniel 
Thank you for your kind words Jan, astute observations and seminal additions as well.
While I am very impressed by the Miller SE-100 engines seriously unconventional approach to the entire concept of a model steam engine, it is also true that they really are not what I would call, great model steam engines, and are in fact a little "clunky" and not terribly good runners, needing lots of tweaking and TLC to get the best out of them. That being said, I still like them very much for their obviously unique features. The engineering forethought that went into their design is most impressive! I am also impressed with the Miller 1000 piston style air compressor, as being a very good and reasonably powerful air source for smaller painting operations. It seems fully the equal of my Binks diaphragm style compressor, which was considered state of the art for model airbrush work in the long ago when I bought it, but it is still far younger than the Miller compressor, though not really far better. Seems a good solid unit that I'll likely put to the use it was intended for someday.
Saito sits at the other end of the spectrum for me. They are of a quality that belies their typically smaller size. After WWII, and all through the 1950's I clearly recall the term "Made in Japan" was nothing less than a joke, but by the 1960's and since, that had turned around to the point where the joke is on us.
Since the late 1960's I have collected imported model brass trains (in HO scale), and the craftsmanship and artistry exhibited in those has clearly exemplified the exceptionally high standards of Japanese manufacturing capabilities, even though only done at a cottage industry level. Then, of course, my years in Metrology and other engineering related fields, has shown me the great strides the Japanese took in providing quality tooling and instrumentation in those fields, which is almost mind boggling! Mitutoyo, and many others, comes to mind here!!!