You should not roll crimp cartridges for auto pistols that headspace on the case mouth. Glad to hear you don't even want to do it. It will lead to problems.

As far as a light taper crimp on .40 handloads ...... It's a good idea just to be sure you won't get bullet set back during feeding from the magazine. But be careful to keep it LIGHT. You don't need much and too much will crunch case mouths into the bullet shank and lead to erratic head spacing, a problem you do not need.

I agree with the idea of taper crimping in a separate step. Trying to set a seating die to seat to the right bullet depth AND apply the right amount of crimp all at the same time is problematic and will lead to a certain percentage of your rounds being either over crimped or under crimped. Probably a small percentage , but who needs it?