Hi Bryan,
after PL has rendered both previews, you can compare instantly (both previews are cached). – Hmmm, maybe there is a difference when you use a common platter, while I’ve checked with pics, database and cache on NVMe.M2.
When PL8 came to the market, I tested that scenario and still use it to compare different NR settings. 
BTW, just now this month I exchanged my GTX 1060 6 GB for an → RTX 4070 12 GB.