I just did a comparison with a great used LP - Oscar Peterson Trio - Night Child (on Pablo today) that had been previously cleaned with the 16.5 using Audio Intelligent fluid step 1 and 2. I listened closely then repeated steps 1 and 2 with the PRC3.
What I was specifically listening for was the cymbals, which are quite nice on this LP, as well as the last track on side 1 that uses small chimes.
I find sometimes on comparisons of gear I like to focus on very discrete details, since they are easier to remember than many instruments all at once.
I have used the wood block sound on this LP before to compare tweeks - it's a simple sound and easy to remember. (I didn't listen for the wood block on the VPI pass, but I remember it standing out well on the Loricraft pass)
On the PRC3 pass, what I heard was a more extended top end with higher placement of the cymbols in the soundstage, and definitely more of a metallic sound. The chimes seemed to image wider across the stage and have slightly more detail. I also thought I heard less pops and ticks - but can't say for sure.
Obviously I'll be doing this test a few more times as I begin to reclean LP's with the new machine, but so far, to my ears it seems like the sonic benefit is there, as well as the usability issues I happen to like.
Is my little test conclusive? Not really since there is no way to know if one more dual pass on the VPI would have yielded better results than the first.
Is this a must have accessory? No, I don't think so - it's rather expensive, especially now. I do however consider some type of vacuum type RCM a necessity. I'm sure there are people getting good results with steam alone, or some other method, but I think they key is to remove particles in suspension under vacuum pressure. How one accomplishes the task is up to them.
I'm just happy I no longer have to keep hunting the classifieds hoping that one day a PRC3 will pop up that no one has claimed before me.