Yesterday I replaced a set of Boomers with Progressives on my Roscoe Beck 5-string. Gauge is M8000 series, .045 to .135" Each string was cut to 4.0 inches longer than the farthest edge of its tuning machine. This allows for two complete wraps around the cylinder and a very easy and clean installation. I don't hear any big difference in tone or loudness between the two but the Progressives do have a few advantages over the Boomers. The Progressives come in taper wound (Saddle Hugger) design for both the B and E strings. If I wish hard enough, I think I can hear an improvement in sustain and clarity on these two strings. I had to raise the saddles on both the B and E to compensate for the lower installed height of the Saddle Hugger strings. GHS designed these string so the core is exposed and contacts directly the bridge saddles. With the Boomers, the wrap wire contacted the saddles, so the strings rode much higher. Intonation and truss rod settings did not require adjustment, so I am assuming the string tension is similar. The Progressives use nickel Alloy 52 which is highly magnetic and should be easy on the frets. The strings were nicely silked, and specifically designed for Through the Bridge stringing on the RB5. They have a nice feel for roundwounds, and this feel is the same as the Boomer series. Emotionally, I like solid Alloy 52 better than nickel plated steel.