It is surprising at how different conditions can challenge
those Miller stability numbers.
Example, a Lyman "Snover" 410663, at 1.375" long in a 16 twist barrel can shoot pretty well out to 800yds and kind of OK at 900, 1000. But if you have twitchy winds especially from 10:00 to 2:00, It will be "spray and pray" at the longer distances. Go down to a 1.325" long bullet, particularly a smooth paper patch bullet that has a 25% diameter "hemi" meplat and it will shoot to 1000yds accurately, and with less issue with the headwinds. Proven at Lodi long range matches.
beltfed/arnie

But going for a faster twist won't affect accuracy with lighter bullets, while giving more versatility in the use of heavier bullets.  I'm more of a 'in case of doubt, go for the faster twist' kinda guy.

Usually, there's another factor coming in if accuracy isn't there, but not so much they twist rate.

I have to agree with oneatatime, I have a NEI mold that drops a 305gr. 40 cal pumpkin (it's hard to distinguish the top or the bottom because of the meplat size ) and it shoots well out of any of the twists I have.  Someone once said it looked like a well balanced bullet.   Both of these shoot respectable but they are ugly in design and take a longer throat as it's not really a bore riding nose.

Here is a couple of PICS of  40-65/16 twist bullets performance
at 100 and at 800yds.  The 100yds is my 1.325"/371 gr DDEPP
bullet now made by BACO, #403380E 
The earlier 2011
scorebook plot of a string I shot is with my 1.325" 370 grain Elliptical minigroove bullet.
The 1.375" Lyman Snover would shoot very well for me out to 600yds, but never at the long range yard lines
beltfed/arnie

Dang, Arnie, that is a handsome bullet and target too.

I have a large number of .40 caliber rifles, as I really like .40's. I also have quite a variety of twist rates, and powder capacities. I've tried bullet weights from as light as a 330 gr. to a 420 grain in all of them.
As mentioned previously, the Snover, or other bullets I've tried with more tapered noses don't do as well at longer than 650 yds. if there's much crosswind. But bullets that are shorter, and have more weight forward seem to shoot better at distance when the crosswinds pick up a bit. They still get pushed off target, but once I adjust windage back in to compensate, the group sizes seem to hold better.
My .40 caliber barrels range from a 1:14" twist, to a slower twist original barrel that's a 1:20" twist. I've shot the Ballard 1:20" twist with everything from the light 330 gr. to my heavy 420 gr. bullets, and it shoots all of them very well with it's 20" twist, at 650-1000 yds. Surprisingly the point of impact changes very little from my 350 gr. load to the 420 gr. load. Likely because the 420 gr. is seated deeper in the case, thus increasing pressure slightly.