I like the concept but I don't understand what it would be for?
Yes i often use more than one lead sound in a song. And none of my lead sounds are the same as my rhythm sounds. So i cant just use my rhythm sounds and enable a locked boost on them.
Imagine this scenario: I play in 4 different bands and as a substitute in many others. Different bands require different volume difference between rhythm sounds and lead sounds. (And sometimes different acustics of the venue too) In some bands you only need a little bit, in others you need quite a bit more. So my solution to this is being able to control the volume of ALL lead sounds PERMANENTLY with the turn of one knob. This approach (that i’ve used for over twenty years) has gotten me the reputation of being the guy who is ALLWAYS spot on with my levels. I never fiddle with volume pedals and screw the first bars of the solo up. Once i’ve adjusted the boost knob on the hardware boost pedal i have set all the levels for my lead sounds because they all have the boost pedal patched in on the effect loop. This reputation for perfect levels and no fiddling with gear has made me first choice as stand in in many bands. And as a consequence of that i never play less than 50 gigs a year.
And if the band gets louder during the gig, but i don’t want to compete in the “all against all volume race” i just raise the volume of my lead sounds a bit (again with only one nudge of the knob) and my leads will sit fine and my rhythm sounds stay where they are.
Or imagine that the sound guy asks you to have the solos louder. One knob adjustment and all my lead sounds have the right levels for all of that gig. No reprogramming and saving of multiple sounds needed.