Well I've 6x SR Purple in my system at this point. They make an incredible difference. I recently changed from an icOn 4PRO passive slagleformer pre to Absolute Audio Labs ASL-1Z pre and found a noticeable increase in sibilance in my system despite being better in most other ways so removed the remaining sterling silver power cables from wall to Musical Paradise MP-T1 balanced isolation transformer, and to Soundaware D300REF steeamer and installed Duelund tinned copper power cables to match all my other components. There was a slight reduction in sibilance. So I ordered an SR Purple for the pre and once more the reduction in sibilance to the point it's only reproducing whats in the recording, as it should.
That said I've SR Purple in my Afterdark Trifecta Emperor Double Crown OCXO clock, Soundaware D300REF, Accurate Audio Ultimate D1000 DAC, Absolute Audio Labs SIT-A15 power amp and Queensway QS-10 sub. Performance is just stunning and I won't cover benefits as it's much the same as others have already described in the thread. I have found one difference not mentioned here unless I missed it is one note bass is gone in favour of natural, detailed and tuneful bass which allows you to better hear the instrument producing it. Probably not ideal for those that like doof doof however for me it's a massive improvement. Very impressed with the Purple or I wouldn't be getting more whenever I change components. They make an enormous difference in my humble setup.