Barrel Roll And g's Quest.

Thare are four differing rolls, aerodynamically.

The aileron roll is primarily around the longitudinal access, there being a
little pitch before the roll.
The barrell roll is a blend of pitch and poll, in other words using two
axes.
The slow roll is a roll whereby the lift vector is moves from the wings to
the fuselage to the wings.
The above three are all flying, and not stalled.
The snap roll is a a spin from an accelerated stall.

There are not four points to consider in a barrel or aileron roll, there are
an infinite number of points. Since pitch is involved there will be some G
forces above 1 on the entry and rollout, however small that difference from
1g may be. With sufficient power and slowness of roll, it is possible to
approach 1G throughout the entire meneuver.

Hope that helps.

Simon