I can find the links but I have a hard time posting them. If you like I could just print one out and there you go. But understand I never said one method is better than another. Only that there are issues with either arm and designers choose them for individual reasons. Your points of lower mass vs. better lateral balance are correct. Allow me a small rant. If there were a clear winner here it is tangential tracking provided it is done correctly and that is expensive. As in all things mechanical the quality lies in the materials and proper execution more so than the particular design.