I am upgrading my Shapeoko 2 for more rigidity. X is 1200mm, Y is 500mm. I want to "knock it out of the park," so to speak, without "breaking the bank" so I am thinking of replacing my V-wheels with a linear guide system. Firstly, I am thinking of swapping the X axis rail (currently 2 pieces of 20x40 makerslide bolted together) to something like 8040 or maybe even 8080 extrusion. That should take care of the twist around the X-axis which is where most of the flex is coming from. However, there is still some stiffness to be had in the way the carriage rides along the rail. The current scheme is delrin V-wheels rolling on makerslide, which is not the stiffest setup. There are some geometry changes I could make to stiffen it, but it will never be as stiff as other systems. I've also found that, unless you use a dust shoe 100% of the time (not practical for me), open wheel systems require a "bellows" (vinyl dryer hose) to keep debris off the rails, otherwise the wheels tend to roll over the debris and cause irregularities in cuts. I would like to get rid of the bellows if I can because it cuts down on usable work area. I am thinking of switching to MGN9, MGN12 or something equivalent like AG15 or AG25 (from Automation-overstock.com or robotdigg.com), bolted to the aluminum extrusion. I don't have any experience using that type of linear motion system. Is this a good choice? Advice please?