that's the sort of detail I was hoping for.
In thinking further about the issue(s) I think nimbleness might be a misleading term; yes, one can feel a difference in the shifting of weight from left to right, right to left, between a higher COG and a lower one (engine weight up high versus engine weight down low, even by inches) but the main impact, especially for a newbie rider, is balance - the "point of no return" where a normal human can keep the bike (relatively) upright is earlier / narrower with the COG higher, versus when it is lower.
This is of course manifest in how a bike handles on the road dynamically, but there I'm sure it is much more complex and the differences are more difficult to describe or even identify by a newbie.
The image you describe - an experienced rider clamboring all over the bike - is a particularly vivid one, and really underscores the much more intimate experience a "rider" has compared to a "driver" along with things like smells, the flow of air, temperatures, etc.
An altogether refreshing and wholly enjoyable experience!
Cheers,
TM