I suppose when you go for the 'L' shape gantry, there isn't many options where the ballscrew can go. This type gantry was deemed stronger than having two separate extrusions top and bottom with the ballscrew inbetween. Some compromises have to be made, and I chose to go with a stronger gantry design.The statement below which JAZZCNC made form the 'effects gantry cross sections' thread reassured me it will be fine.

Quote Originally Posted by JAZZCNC View Post
I've built machines using the green design and please believe me you have nothing to fear the strength is easily over the top for anything but steel or harder.

Yes it places the ball-screw slightly further back than what's considered ideal but again it's nothing and doesn't make any difference to how machine performs. The positive is the screw is away from the firing line and protected.