In light of the all round astonishment I went and checked the actual numbers, rather than off the top of my head - it was 44% removed.

So still way better than I'd expected.

Have to say I haven't done it your way round - we've completed three rounds of email outreach then submitted a disavow file, so I don't want to guess to far on advisability of doing it the other way around.  For starters I've no idea how well / quickly Google handles domains removed from a disavow list.

Your first assumption needs comment though - every domain we're removing links from was from a spammy website (zero quality SEO directory), as a result of a submission package they bought years back before I joined.

We managed to get about 50% of the list removed from that email outreach process.  Granted one was a directory network with over 100 domains, but even counting their domains as one that we got about 40% success.

Around 10% responded with a demand for a fee - ranging from 99c to $50.  Clearly all those were instant place in disavow list

So to summarise I was really surprised how successful the email outreach part was - we'd been expecting next to nothing by way of response rate rather than around 50% success.

Even if you do it disavow first, hoping for a Penguin update in the next three weeks so the file is actioned prior to your season starting is a little optimistic!

Blog and forum comments containing links are almost universally rel="nofollow" meaning you'll get no value from an SEO point of view.

Course that does precisely nothing to discourage the blog spammers.