The Fillet Pro reacts and flows much differently than bronze. Much less heat, watch the flux, and really pay attention to when the silver melts. It moves fast! Tiny flame and great heat control. I really like brazing with fillet pro, but I only use it on stainless or attaching stainless to 4130 (financial reasons). I haven't played with system 48, and I stick to Fillet Pro with Stainless Light. Cycledesigns has a good write up on System 48 on their page.