I developed my first roll last night and have scanned a few images. I will try to post images or links this evening if I have the time.
My initial impressions:
The film comes on a gray base similar to that used by Harmon and Foma. There is no color change when developer is emptied (no antihalation dyes are removed). There are absolutely no markings of any sort on the rebates (UltraFine Xtreme has the name printed on the rebate).
I developed in XTOL stock for 7m 30s at 69 degrees (room temperature). My initial images show more contrast than Kentmere, HP5+, or UltraFine Xtreme. The negatives appear somewhat dense, but it should be noted that the images I have scanned were shot with a Leica IIIc from 1949 at 1/1000s so I suspect a little overexposure was built in. Despite that, the images scanned well. Grain was pleasant but not obtrusive. I also found the images quite sharp. I actually prefer this film to Kentmere, HP5+, and UltraFine Xtreme.
My initial impression is that this doesn't look like any Harman film I have shot (I have never shot Ilford Pan, however), but that could just be due to differences in exposure or development. Since Harman was shut down for several months due to COVID, it would surprise me if they had time to make a small batch of film for UltraFine Online so it is likely they sourced this film from somewhere else (warehoused film or a different supplier).