Sebi, that is alot better cct then using a plane old opto-coupler setup
The worst thing abt using opto-couplers in their linear region to isolate an analogue signal is over time as they age their linearity severly deteriorates.
With the method there is a feedback of such a deterioration. However, the downside of this is, as the opto starts to deteriorate (and it will after not that long), this closed-loop will over-drive to compensate, and thus age it faster.
Admitidly it will last alot longer (as in with usable characteristics, plus general use) than no-feedback.
That leaves only two other methods for anaolgue isolation.
1) AM over an isolation XFMR
2) digitise it and serial it over an opto (in its descrete mode, where it lasts alot longer, perfromance wise)
with 2) it is worth looking at magnetic isolation chips IL71# range
https://www.nve.com/webstore/catalog/product_info.php?products_id=58
extreamly high datarates with isolation on par with optos, thus you can still get the resolution. One warning, be careful with the power supplies to these chips and also fields - I tried these chips (out of interest) in a gatboard to switch 800A at 350V and they kept being influence by the fields.