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I can't comment on comparisons of one non-descript refractor can supposedly do against another.
However, in my personal experience I have been able to compare a f7 TV-85 against a Vixen 102M which, IMO, was an excellent F/10 achro refractor as well as a Vixen 140 and a host of Skywatcher big achros up to 150mm. On every occasion there was simply no contest, with or without any combination of VR filters etc the TV-85 beat the clappers out of the others in terms of the crisp, clear and detailed image rendered of Saturn (for example).
However, two important variables (both of which Wavy mentions) to keep in mind. First, and most important is LP and thus your location. In a suburban light polluted back-yard I couldn't see any difference in DSOs between a 140/152mm refractor and the TV-85.
Second, quality of eyepiece does make a big difference. You need to be consistent the whole way through with the optical path. Probably the absolute best eyepiece for the 'specific' parameter of light pass/contrast are the Pentax XWs. There are many other excellent eyepieces which are superior on other attributes but for this specific variable in viewing DSOs through a refractor I found the XWs to be best.
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