The OP is asking for a comparison with LR, not ACR
I am not sure if this surprizes you, but LR is using ACR.
So no sidecars unless you want them for some reason - the data is stored in LR's database
I mentioned the sidecar files, for I find them an advantage
compared to DPP (and compared to storing the adjustments in a data base).
LR does allow multiple alternative renditions, via both virtual copies and snapshots (concepts which need pulling together). Only the latter are stored, if you want, in the xmp or dng
Are you sure, that multiple adjustments can be stored in XMP format? I don't think so, but I am not sure of that.
As for the colour reproduction issue, that's only a matter of opinion and many would disagree with you
1. It is not a matter of opinion, that the color reproduction of ACR differs very much from that of DPP.
2. Adobe acknowledges, that a calibration should be done.
3. Those, who have done it, confirm, that the result is better, but still not the same as DPP.
4. I have yet to see one, who prefers ACR's uncalibrated colors to DPP; you might be the first one. However, there are many (like myself), who are either lazy, or don't appretiate the accurate color reproduction as much as some others do.
How far the above is true is confirmed by the upcoming features, which allow for multiple color profiles.