Hi, Mike:
You can use Prores in SD without any problem.
I found that if your content is going to internet or maybe you are a student with a short film even some Panasonic cameras, like the AG-AF100, recomends Prores LT . Is just fine and it takes less disk space. Prores is the standard and it ok, altought my guess is that in most cases LT is just what you need, I would recomend you to not use Prores HQ or 4444 unless you were planing on doing keying or extensive color correction.