The people who designed these loved their craft and it sure still shows.
If the beautiful blue meters were already announcing what was to come all too quickly (lights, flashing leds and mute electronica), the RT-909 probably is one the very few units that properly embodies the fair balance between efficient modernism and great work.
The 909 is powered by three motors within a closed-loop dual capstan path, has 4 heads (the 4th being for reverss playback) and fair but not exceptional specifications - we're not in TC-880-2, RS-1700U or even GX-255 territory.
Seeing a 38cm/s or a 1/2" tape version probably would have allowed to cut some sales off the Technics RS-1500U and secured the RT-909 a place in the audio museums or more audiophile studios...
If the equally successful RT-707 was mainly export, the 909 was a strictly export-only item which sold extremely well in Germany where it remained available until 1984 (!) and the USA.