I tried using the magnum on the bow eye in a heavy chop on Winnebago and didn’t like it as much as running the small one. It slowed me WAY down, but it also caused a surging that made it tough to control the steering. It may work well in flatter water, but the small has always worked well enough for me to not need the big one.
On my old boat, with a 75hp, I could slow my trolling down to around 1.6 or 1.8 using the small sock.