i am a pro I-Car certified autobody tech.
the VW certified shop i work at has a welder that welds aluminum, silicon bronze and mig with the same unit. there are 3 different wire feeds and torch ends. it also electronically adjust itself and uses pulse tech for better welds..

this is the welder. i THINK the purchase price was around $20K. https://prospot.com/products/sp-5.3/

mig welding with silicon bronze is referred to a MIG BRAZING welding.

i weld patches with silicon bronze ALL the time. it works excellent for that. the best part is their is significantly less warpage with it. it also works fantastic for butt joint welding.
also I-Car recommends using silicon bronze for welding ultra high strength steel in certain areas. they also highly recommend using it when welding near ultra high strength steel.
also when when MIG Brazing use longer stick out to pre heat the wire so it flows under the panels for better adhesion.

i am not sure how you would set up a regular mig to weld silicon bronze properly. i can tell you using silicon bronze has faster wire speed with less voltage than regular mig welding. also when welding with silicon bronze the finish welds look significantly colder than a mig weld.