Excellent post, Scott. I remember talking with you about some of these differences a while back, and you've laid it all out quite nicely here as well.
I've been thinking for quite some time that I should get a full API node up and running and this has me thinking all the more how important that is for top witnesses. I look forward to hearing more about your build when you release details. Hopefully we'll continue to see improvements to how Steem manages data so we won't need expensive, experimental servers or days of replay time to run full nodes.