Haven't read the whole thread yet, but just thought I would chime in. I have changed my oase biomaster 600t for a jbl e1902 and the flow rate is night and day. The water has never looked clearer as I can now have a big wad of floss in one of the trays. What I don't like is that the jbl sounds fairly loud hum in comparison. The hoses are a lot bigger which isn't a bother for me, but if you any anything inline then it will be an issue.
Ideally I would have taken a punt on the new aquael filter as it looks really good, but it was a couple of cm too big to fit in my cabinet