Personally, I wouldn't mind having to wait one second before adjusting the delay time. For reference, the amount of time you have to hold the encoder to save presets is perfect – definitely not an annoyance.
I think the existing catchup feature, which is great, was implemented to address this same issue. But in some cases, especially with the delay time knob (when dialing in ms), you're not always able to see your starting point.
Another suggestion would be to display existing settings whenever a knob is touched, and force the user to scroll the knob back to "0" before they can adjust settings – perhaps this is already similar to the "lock" function you mentioned.
To restate the problem, It's very difficult to edit an existing delay time by a few ms…