I almost always prefer a very soft, diffused
edge to the spot. While I can see why I would want a hard-edge, blatant full-body spot, I have not had to use that so far in my designing career. What it comes down to is what you as a designer want to use your spots for. In most of my shows, I consider the follow spot to be a supplementary tool to add a little brightness to a certain person, which subconsiously draws the eyes of the audience to them. Ideally, the audience wouldn't even realize that the person was being spotted, they'd just have their eyes drawn to that person (remember, the audience tends to look at the brightest thing on
stage).
Were I lighting a show like
Cabaret, I would probably use very obvious, hard-edge spots on performers for the
Cabaret numbers. But again, it depends on your design and your
vision of the show. Right now I'm lighting a production of Titanic: The Musical. It's almost easier for me to think of it as a "straight
play with music" rather than a musical, since the lighting and sets and such are made to be as naturalistic as possible, without many surprises or unnatural things. For this show, I am going to get my spots as soft as possible, because letting the audience even see a little
bit of a hard
edge would destroy the "non-theatrical" illusion that I want to create.
I'm interested to hear the opinion of others on this one. See if some of the old-timers here enjoy the more traditional look of a hard-edged spot.