Actually the IMCR vis minimum is 1800 metres which is now an anomaly as a vanilla PPL can legally fly in 1500 under EASA. The same is true about VFR on top an EASA PPL holder can now do that.
The main benefit of the IMCR is to be able to accept an IFR clearance in controlled airspace other than Class A and to fly instrument approaches, these privileges are currently restricted to the UK.