I use the max load listed of HP-38 (actually I use Win 231, but data is identical). The powder meters very
well and I get very respectable accuracy. Powder fouling seemed to get lighter the higher my powder charge went, hence the reason I load to the top of the chart. My XD hasn't shown any signs of high pressure with this load.
I have recently begun experimenting with Longshot, loading some +P 38s for my LCR, so I can't expound on it's use in auto cartridges. I will say, though, it gives screaming velocities at what seems to be moderate pressures, so if you're looking for a thumper load, it might be a good place to start.