I'm doing different tests on new sites each with similar comp, each with one thing changed. All the sites have the same basic SEO like 25 web 2.0 links, 25 bookmarking links, a few directories, etc for diversity. Then one site will go heavy on high pr comments, one with xrumer/sb, one with PBNs, one that's 301'd, etc. In about a month or two I'll go with what works best, right now sites are dancing too much to judge, but high PR comments with low OBL might be a winner. Done manually and not in huge numbers, that's pretty white hat. But I'm skeptical of case studies right now because Penguin seems to be inconsistent, maybe in time as it's updated that won't be the case. Two sites with the same on and off page seo in the same niche can have one penalized and the other rewarded.