I have Chris's fixture, and while I do love it, I only use it for the hard phenolic tips. The softer ones seem to tear more than cut, and get fluffy in the process. I have finally mastered the razor method, trim it in reverse then shape going foward. I really like the fact that everytime I do a tip, I grab a new razor, VERY sharp no question. If you buy the specials at Depot or Lowes, you get 200 for $9-$10. They literally cost .04 and they have a sharp edge and no time wasted trying to sharpen a skew and no money tied to a stone, oil etc. After I use them on a tip, I then put them in a container to be used to scrape off the crap that spills on the bed of the lathe, or floor, on the kitchen table, cut open a bag, anything. If the cost of .04 for a blade is a concern for a $10-$25 tip replacement, then......
As far as safety, how many have cut themselves using a razor to trim? A lot of people have expressed concerns, but I haven't seen any one say they have harmed themselves this way, yet. I'm sure it can happen, but the same can be said for every method. Everytime we turn on a machine, we take a chance. Tools don't make a job safe, our own attention to what we are doing is what decides the saftey factor, IMO.
Not knocking anyone elses methods, just this works for me. The guy that works our APA regionals uses the metal sander while spinning in a lathe. He is from the old school ways, and it works for him, but I can trim a tip in 1/4 the time with a razor.
Another thing I've noticed is, no matter how much time we spend getting the shape just right, the customer takes 2-3 shots, pulls out their shaper or hands it to some that has one, and screws it all up anyway. So in the end none of it matters

Dave