So she rode the bike again, this time off-road, which is good. Had some issues with the brakes which was surprising, sounds like the pads need to be either resurfaced or replaced - lots of noise and very little braking. Unrelated to the frame, though, and easy enough to fix.
The big thing, however, the leg strike issue with the wider seat cluster -- seems resolved. Thanks to the really long support rails on the SP4 seatpost, I couldn't get the saddle forward enough. Swapping posts fixed that, and the saddle-to-bar now matches her Scale exactly. When she was talking about the bike, she didn't mention it, and when I asked her, she thought for a second before saying it still happens occasionally but it's not such an issue. So, I think for most folks it won't be an issue at all unless you have the same combination of a low seat relative to the frame size and a very set back saddle.
With the bike set up exactly like her Scott in terms of geometry - and all the parts on the bike having done duty on the Scott before we upgraded to better - it now comes to the comparison of the bikes. She still thinks that the fit isn't quite right, which is odd because the frame geometries are exactly the same and the key measurements are the same, but more importantly, she thinks that while it's nice enough, it's just no comparison to her Scott.
Direct quote: "It's good enough - just not my Scott."
Of course this isn't a direct comparison, even if all the parts have been on her Scott already, it's got far nicer parts (new XTR vs old XT) plus a better fork (new Fox vs older Fox) and massively better wheels. Plus, it's far from a single blind test - she knows which bike she's riding and I'm sure there's some bias sneaking in there.
So, at this point, looks like the Chiner isn't going to be much past "backup bike" status, although hopefully once I take care of the noisy brake issue I can get out on a ride with her and see if I spot anything.