Regarding the roll crimp in a convertible cylinder, two things. One, with a proper, firm taper crimp I never ever had a single issue with bullets migrating forward. Two, I have an RCBS roll-crimp die that I used for many years for all my .45 auto cast bullet ammunition and again, never ever had a problem with headspace. The largest throat entrance I ever saw was .455" and the smallest the roll-crimp die can make the case mouth is about .463" and that's an extreme, ruinous operation. Rolled to about .467" (same as I make my TC with the Lee TC die), headspace cannot possibly be an issue unless you use a bullet with a crimp groove, crimp IN the groove, and use a die that rolls the case mouth down to bullet diameter.
The "cowboy" brass is a solution looking for a problem IMO, or a market-driven fluff item.