I'm so glad you decided against the Furminator. It's terrible for Sheltie coats! It cuts the guard hair which you don't want to do to a Sheltie coat. A shedding rake is much better. I have a simple wooden-handled one that takes out tons of fur. Here's a link to something similar:
http://www.amazon.com/Conair-Short-...446847381&sr=8-19&keywords=shedding+rake+dogs
If you get the CC pin brush, I would get the 20mm pins.
I have a few of the Chris Christensen brushes, and they're good, but I love my Madans! They're cheaper and do a great job. Be careful if you order them to get the right pin strength. You probably want a Medium...they're color-coded. You can find them at
http://wicketsbymel.com/madan.html.