By convert, do you mean, to use as a shaving soap?.......
I did try Yardley's tablet, hand soap a couple of years ago as a shaving soap..but only because of the lavender scent, which reminded me of the fifties Yardley shaving soap...Only used it a couple of times to shave with, not really in the same league as a dedicated shaving soap like MWF...though at a pinch you could get away with it if nothing else was available..The lather was good to start with, but it didn't last....the slickness wasn't as good either.....
As I remember my dear old Dad only ever used Fairy toilet soap to shave with...and he made one DE blade last all week....ouch.