It is a misconception that fast powders are producing lower PEAK pressures because they produce lower velocities.
In the 40 S&W, there are some pretty heavy bullets available (mainly intended for the longer 10mm cartridge), which leave very small amounts of space for the powder when the S&W is loaded to its normal length. There have been reports of pressures getting spikey when powders that are too fast are loaded under bullets that are too heavy in this cartridge.
So, the OP seems to be headed in the right direction for recoil reduction when he chose a lighter bullet as well as faster powder. I shoot Clays (not Universal Clays) over 155 grain plated bullets for my light recoil load. It is clean and miserly at 3.9 grains per pop. However, the range from start to max load is only 0.4 grains, which requires special attention to loading processes to avoid accidental overcharges. So, I would not recommend a powder that is THAT fast to a new reloader.
The HP-38/W-231 recommendations are probably about right for a new reloader who is looking for a reduced load in this cartridge. It works fine for bullets in the 135 to 165 grain weights.
One thing the OP will need to deal with is that the same recoil does not FEEL the same to everybody. For the same momentum / "power factor" (i.e., bullet weight x muzzle velocity), some like a lighter bullet moving faster, while some like a heavier bullet moving slower. Proponents of each opinion have a tendency to try to explain their preferrences with discussions about pressures, bullet acceleration in the barrel, etc. etc. etc., with some bad advice sometimes creeping in with repsect to load data.