I admit to being more clueless than I should have been. I didn't realize they used V-screws on the solidoodle, nor frankly did I think about what a V-screw is. V-screws are not great for use as a linear actuator. If you imagine a V, well, you're pushing against that slanted wall when you turn the rod (and have a nut that moves along the rod.) Only the vertical portion is actually going to give you linear movement along the rod, as in, the |_| portion of your rod's thread.
In that sense, acme rods are designed for linear movement. They're threads are much more vertical.
However, when i say they are bad because they are high friction, I think I poorly spoke. Because they are better for use in a CNC machine (3d printers are technically cnc machines, I think.) However, all of the rod based systems are "high in friction" because their basic principle is that of a worm-gear. And especially where the X & Y are moving quickly, the static friction and intertia of the rod are very high. If you want to make a bigger solidoodle the problems multiply, because thin rods bend easy and the wobble matters more as the length increases. So not only does the inertia increase because your rod is longer, but you start to need to consider getting a bigger rod.