thanks to rectravel for posting the link above
I came through this crossing again yesterday - nothing much has changed since I posted that Lonely Planet Thorn Tree info except that the roads have almost completely dried out and there's no longer any chance of getting bogged down anywhere between the Anlong Veng and the border, and only a couple of remaining mudholes worth mentioning between Siem Reap and Anlong Veng
left Siem Reap at 13:25 by pickup truck, arrived in Anlong Veng at 19:20 (20 minute stop at Sre Noy; last 90 minutes or so in the dark)
next morning, Anlong Veng to the border in a very decrepit and patiently driven pickup - about 30 minutes to crawl to the bottom of the escarpment, about 20 minutes to coax it up to the top; from the border, the 16km of unsealed roads on the Thai side took just under an hour in a 4WD which rarely got any further than second gear
FWIW in the opposite direction at the beginning of April in a rapidly driven share taxi: left Anlong Veng at 12:50, got to where the sealed road starts at Banteay Srei at 15:20, arrived in Siem Reap at 16:00