After 30 odd years of desiring a classic SYW Yamamoto F/15 108mm / 1500 refractor [same OTA as a Tasco 20TE]. I discovered my local optics dealer had a mint condition one with a pedestal mount in storage. I sold my Skywatcher Equinox ED120 [EON] on a HEQ5 mount with in a week to fund it. The sale price of that combo basically covered the price of the 108mm - which really was a bargain.
The images in the 108mm F/15 are incrementally superior to the ED120. The Synta ED120 really was very good optically - flat image with CA only really apparent in the higher mag range. Yet the long tube F/15 gives more satisfying images - the color is more neutral, the image equally is flat and CA is only really noticeable with higher mags. in the 250x plus range. The key difference I believe is that the long tube achromat is less susceptible to atmospheric conditions. In steady conditions CA is about equal but when the air is unstable the classic refractor holds its image better and ultimately display less CA.
Brightness is perceptibly brighter with the ED120, as to be expected, but when in comes to pure image quality and on axis resolution the long tube F/15 classic refractor wins.
The classic white long tube refractor also looks stunning and really it is a work of optically industrial art.
Even my wife likes it.
Chris