I also have Mentor and I find Anni more mids forwards. A problem I had with Anni (I sold it) was the resolution. What you wrote about Mentor in comparison "really rich" was "resolution" for me. Anni was plastic here, not textured or grainy enough in comparison, if you know what I mean.
Today is two-years birthday of my Anni ('21 revision) and i am sure she will spent many time in my ears, since it is really perfect for my tastes and my library.
Regarding
@grumpy213 review and the mids, i can say that for an year and a half i had the combo P6pro (the black one, not vocal centric like the grey) + anni, and to be honest, i never liked very much the pairing. Yes very fluid and musical, but too smooth and yes mids recessed and not so resolving (microdynamics and so on..)
For that reason i had always used an external amp in my chain: first the C9 (better but not perfect) and then the Aroma Stack (A100TB + PSPRO).
I must say that with the latter, with its ability to change the OPAMP in both input and output section, i found a great pairing and a great sound correcting all the things that i didnt like direct from p6pro.
I must say that, Anni likes a great quality amp section to really shine, or, let's say, the '21 likes for sure.
Fast forward to last december where for a series of events i had to sold my p6pro, and i found a really good deal on a cayin n8ii ROHM dap.
Well the n8II with anni it is a wonderful thing, expecially in tube mode and class A, no P+. Everything it is in the correct place, mids are not more recessed (but no hyper-forward), bass is really present and textured and not more dry. Resolution, staging, everything is a match made in heaven for my ears and my library (i don't stream, all my music on a 1TB microsd card)
Needless to say i parted also with the Aroma stack and with the tons of OPAMP i had.
My 2 cents, and as usual, IMO and YMMV and so on.