Just a bit more data from my recent experience.
Put a Novritsch order through on the 31st March containing a RIF above the £135 threshold. UPS delivered it today, parcel completely intact, with no sign of any tampering from Border Force. The packing slip sealed to the outside describing the RIF with my UKARA number on the reverse hadn't been removed either. No mention of UKARA anywhere else on the package. No additional imports fees were required, but the shipping line is described as 'taxes prepaid' if that carries any weight.
The UPS tracking on the other hand was terrible - a combination of vague updates and a rolling scheduled delivery date. I'd definitely take any scheduled/estimated delivery date with a pinch of salt and wait for the tracking to say it's departed the facility.