I've been using one for the past 2 yrs. Is it worth it and does it work?....well, in my opinion yes. So far, with the use of the ASD, everytime I spin test an arrow, it is dead on.
It is kinda awkward to use at first but once you get the technique down you can do an arrow in seconds. I shoot carbons and cut and build all of my arrows. After cutting an arrow I use the ASD carbon on the tip end and the nock end of my arrows. I then glue in the insert put in the nock and then spin test the arrow. 95% of the time thats all that is needed, everything spin tests great. Every once in a while I will have to use the ASD aluminum cutter on the insert, but not often. I think some of the insert surface ends are not square to begin with.
I just like knowing both the nock and insert ends are square and in proper alignment.