You might be right, but using basic ETA/Unitas on a watch worth a few grands is abit odd. No qualm that the basic movement is one of the most reliable for the moment.
wow! let me cross....UN..Chopard....GP...IWC..LW...Hublot...Cartier...etc of the list too. So a Big Mac on Noritake makes it an upscale Big MAc?
There are tons of expensive brands using "basic ETA/Unitas on a watch worth a few(sic) grand"
not defending OP here but their decision on that has came back and bite them on their very delicate and upscale arse. but there are also tons of other far more expensive watches using the same business practice albeit in a more sophisticated package e.g. putting Mr Os in a Brioni suit and passing him off as James Bond.
Mr. Os?

Anyway, I think OP messed up on the PAM00318. Not big time, but still a mistakes in a number of mistakes they made along the way. Part and parcel of growing up I guess (not defending OP). They should stop all these micro SE models.
As for using ETA in a watch, not an issue really. Most of the big boys (as listed by terrenceterrence, not forgetting most of the Swatch Group) have and am using ETA movement in their watches. The movement is robust and reliable. Why re-create the wheel? Even Selita base their movements on the ETA. Even TAG Heuer does it (based on a Seiko, which says a lot for Seiko, since TH has Zenith as a sister brand).