Good question. I have had a hard time finding answers too. I'm interested in building my own arm and finding any information regarding how to get going and some pro's and con's to different designs, materials, mass and geometry is a tough one. If I find anything more than bits and pieces I'll let you know.
I just rebuilt a vintage Empire deck and it plays very well. It has a Grado cart and just the stock high mass arm. I was thinking of selling the car for a nice dynavector or sme arm. The busses run pretty regular around these parts, so what the hey.