Semi-auto pistol rounds ALWAYS get taper-crimped as a discrete die step in my RCBS tools. Taper-crimp seating dies by RCBS have caused inordinate OAL variations for me with cast and jacketed bullets when seating & crimping at the same time in the past. My 9mm and 45 ACP seater dies from the early 1980s have a slight roll-crimp shoulder as part of their machining, and I think its purpose was to fold back the case mouth bell. Whatever works--these days I use a separate die step for final finish on my 9mm/40 S&W/10mm/45 ACP. As Lamar stated above, reliability trumps accuracy, esp. given the usual consumer of my reloads' skill set--ME.
Only levergun and revolver ammo gets a roll crimp--and not much of one, at that--just enough to prevent bullet movement. Bolt rifle ammo NEVER gets a crimp, and I have yet to see a need to crimp self-loading rifle ammo through dummy round testing. I don't load castings in my gas guns (yet), and if that occurs the loads will get a pretty thorough dummy round testing cycle to assess bullet "stillness".
