For us the least useful feature is DNS load balancing. We already have a cPanel DNS-only cluster, so we have no need for that. It also seems a little funny that you put config guide at the end (although that's not what the text of the post says).
We'll look forward to this and test it, but in all honestly, I'm not sure how much sales traction we'll actually get. We offered HA in another product line we have (not web hosting related) and most clients were interested until they figured out they had 2X the server costs (dedicated or VPS). When they sat down and figured out what the mostly cost vs. the small amount of downtime that they typically had, it did not end up making a lot of sense to most customers.
The HA also added a fair amount of complexity in upgraded. Things like MySQL upgrades immediately come to mine. It's trivial (thank you cPanel) to to upgrade MySQL, but if you have a replicated database, that's going to get more complex.