For a data point, yes, I experience .5" increase in MSEG while doing girth work. It doesn’t happen right away, but takes at least 10-15 minutes to get there. I use that number as a measure of what I consider to be a good workout.
I started at 4.625 mseg, got up to 4.75 doing stretches and jelqs and stayed there for a long time. When I started clamping (manual or with a clamp) I would notice .375" increase in girth during the workout. Over the past few months I have pushed the intensity while still being mindful of safety and thus, the .5" difference.
In June my non clamped MSEG was 5.0" but clamped it was 5.5. Now, in September my non clamped is a bit over 5.125 and my clamped can get up to 5.625. So, based on my experience, I would say, yes, expect your clamped MSEG to stay .5" above non-clamped.
And, for what it’s worth, I never could have imagined it being that big. Seeing it that big during the workout is really motivating. I wish both of us continued girth gains.