For rock solos, most players require additional gain for sustain and a hike in volume, which would explain the dirty nature of the tone of this unit. The delay allows for a warmer tone, too.
There's no way of altering the delay parameters but, as it's set lower in the mix, this is no bad thing. For Vai-style emotive lead sections with the neck pickup, the tone is nigh on perfect and riffing with power chords is equally satisfying.
Perhaps reverb could've been added to the Acoustic unit, too, because the delay makes all the difference to the sound here.