Hi,
I use a system that was built from a Quattro as a donor. The original Quattro, as far as I know, is a pretty reasonably performing scope. Obviously, at this price point, you will have to live with some "limitations". The optics in itself are pretty good; the mechanics, I assume, are probably alright but not exactly "premium". My biggest concern would be the focuser. At F4, you really cannot have any flex or tilt in your imaging train - which requires not only perfect collimation, but also mechanically stiff components. The stock focuser might be alright, haven't used it. But I have used a similarly priced Newton way back when and that one had a terrible focuser
Also, if you come from a flatfield APO, the process of taming an F4 mirror system will probably be a bit of a challenge. It's doable, obviously, but it creates some overhead you are not yet used to.
Regarding the Esprit 120 - I also happen to own an Esprit 100, which I can warmly recommend. I assume the 120 is no different - a well-performing, low-maintenance scope. The speed is an issue of course, but F5.5 is not too bad, really (basically, you need to collect twice as much data compared to F4). But it really is very much plug-and-play, most of the time. I have not yet lost any time imaging due to scope-issues, whereas the Newton cost me many a night due to collimation issues etc. I am however very, very picky about this sort of thing. Others will happily live with slightly elongated stars in one corner.
Either scope will require a fairly robust mount - EQ6-R or above, I would say - if you plan on doing long-exposure astrophotography.
Good luck with your choice!
/Marc
