My thought on the effects of g-forces is the exact opposite of Psion's, but for similar reasons (if that makes any sense).
If the gravwell is pulling space forward (bending space towards the ship) and pushing space away from the back of the ship (bending space away from the ship), then the spot in between the two gravitation forces is, in essence, at a standstill. It isn't that the ship is moving through space, but that space is moving toward the bow of the ship and away from the stern of the ship.
If I had ANY artistic ability whatsoever, I would try to draw what I am trying (and failing) to explain.
Of course, if your fan fic requires the use of g force limitations, then by all means, use it. Just an alternative view for you to ponder.
BTW, the concept is very well presented in terms of it having some semblance of actual science ability. NASA said that something like this might allow for FTL travel, and even had an artist's rendition of what it might look like. Although I can't find it now. I am sure someone else on this board has a link to it, since I saw it here first.
Also, the art looks great. Can't wait to see more.
What art program are you using?