Nominal 12ga. is .729.
Your bores are typical Beretta tight. No problem tubing from a bore standpoint.
Briley can put tubes in a thinner barrel than can someone using Tru-Choke tooling.
They also have options a pre-fab system does, they can do more custom work.
There should be no difference from a pattern standpoint either way.
I don't know if your gun has chromed bores. I had one that that did (SKB) and that made the decision easy since bore and choke work looks like hell on a chrome barrel. It was pricey, but the stainless tubes are more satisfactory to me than grinding out chrome and leaving it like that.
Recessed choke (jug) will solve the long parallel problem if it's really a problem.
If it's not chromed, I'd be tempted to just go with 5 and 15 and call it a day. I can live with that.
