I have ran most of the powders mentioned here over the years in 300 Whisper/Blackout and most of the issues mentioned are the same.

Hodgdon used to have a warning in either their FAQ or reduced load section, warning to not reduce loads more than 3% instead of the normal 10% when using H110. 

I do personally know of one time a rifle was damaged using a reduced load and H110, but the situation was as described earlier in revolvers. We think what happened was due to erosion in the rifling. This allowed the bullet to jump and stop. At that point it was easier for the pressure to exit the magazine than to move the bullet.

H110/296 are most predictable with a 90-100% density. Below that ES gets high. Above that under compression, there always seems to be a tipping point where pressure stops building linear and starts building exponentially.

Lil'gun runs hot, so barrels heat up quickly and velocity changes. There is a lot of talk with revolver guys about erosion with forcing cones using high end of the chart loads.

The Shooters World/Lovex powders are basically Accurate powders. Explosia says they are using the same recipe's as when they supplied powders for Accurate. Accurate says "not so". 

I have used the Heavy pistol/D037-02 as a direct replacement for #9 with no more variation than you would expect from a lot change. You can interchange those powders in Quickload and the results are exact. Something that can't be said when running H110 against 296 in the same version.

Using Shooters World Blackout as a substitute for 1680 needs about a 6-8% reduction to maintain the same velocity, but it burns much cleaner.

300 MP might be a very good choice for the 32-40. It take 3-5% more powder to hit H110 velocity, but will have less pressure. It also seems to tolerate compression better.

Sadly I have no direct experience with the 32-40, only with the powders mentioned.