Thanks for the replies guys. This site has a lot of valuable information, experiences, and opinions. I'm realizing that many opinions differ, which just means I'll have to try them all myself to find out.
I ran across a really informative post (albeit long) on yeast pitching that really makes a lot of sense (it's measured): http://www.homebrewtalk.com/f163/why-not-pitch-your-yeast-cake-166221/
. I think it probably will probably fall right in line with your recommendation to use 1/3 of the yeast cake.
Here's my situation:
Brewed a 10gal DIPA 6 days ago (put into two 5gal glass carboys), using WLP007. Target OG was 1.09 but we were WAY off and only got to 1.068 (I think I know why, but won't get into that here, I'll try my fixes first). I did a starter and fermentation seemed to go really well (started within the first couple hours). I have 2oz Citra and 1oz (both leaf) to dry hop into each 5gal. I want to capture and reuse the yeast (I have links to good processes for doing that).
Here's my question:
A - On day 7 (either that or I wait until day 14 since I'll be out of town) rack to and dry-hop in secondary and capture the yeast from the primary.
B - On day 7 simply dry-hop (in muslin bags) into the primary and harvest the yeast when I go to bottle.
I've read A LOT of posts on using secondary vs just staying in the primary, but since I want to harvest the yeast AND dry-hop, I'm not sure what the best route is. Any recommendations and why?