EchoTest certainly isn't for everybody, so I understand if you don't like it as well as the Belew stuff. But -- which EchoTest albums have you heard? The last two, From Two Balconies and Daughter of Ocean, are very different from the first two, featuring more vocals and more instrumentation: They sound much more like "rock albums" than the sparser earlier stuff. So if you've only heard Fourth Dementia and Le Fil Rouge, you owe it to yourself to listen to the latter albums.
Also, have you checked out Julie's two pre-EchoTest "solo" albums? Each is populated with an amazing assortment of guest players, varying from track to track, including Robert Fripp (via sampled soundscapes) on three tunes from the self-titled Julie Slick, and an appearance by Adrian Belew on one tune from Terroir. Both of these albums are now available for free listening on YouTube, so you can try before you buy:
I haven't heard any full albums, just random tracks and concert snips, but it's actually the other way around, I liked the weirder slightly more experimental incarnation of EchoTest better than the new more rock oriented and slightly more mainstream incarnation of the duo, still not enough to listen to any of it for the pure sake of enjoying the compositions though, outside of curiosity and respect for Julia Slicks obvious talent, and I still like Adrian Belew's stuff better.
I hate to say this, cause I really do love Julia Slick's bass play and think she is a very talented musician, but somehow it comes off to me as trying too hard to be artistic, and failing due to lack of real substance, this goes especially for the newer incarnation of EchoTest.
Don't get me wrong I love weird and artistic music, that is if there's a real point with it and it is used to express something with real substance, weird and artistic can still be interesting just for the sake of it though, but it isn't likely something you feel much like going back to really.
But I do actually seem to recall having heard some tracks long ago by a project she had with her brother at some point, "paper" something, if my memory serves me, on Bandcamp, and I actually really liked that.
PS: Haven't heard those two albums you link to, listening now and will get back with a comment on them when I am done listening.
Edit after having listened a bit to "Mela":
I really liked the first track on "Mela", reminds me of a somewhat post rocky instrumental Mr. Bungle and perhaps I detect a slight John Zorn vibe, the second track is great too, sounds like a happy musically talented psychotic could have written that piece, I like that perspective, definitely promising, and much more me than EchoTest.
Will get back and listen to the rest.