Just thought I would update for anyone riding in the future. Info as of early March 2012.
The 722 road looks like a nice short cut, but it isn't a complete road. At least 20kms is no more than a path. It is passable by bike (or m'bike) but it is tough going (I didn't ride, but was told by cyclist and m'bike rider). There is no accom, but villagers may put you up in their houses. The cyclist - a Greek guy, said he was in a house and got told to move on by the police as the house wasn't authorized. He had to cycle 25kms in the dark with the very embarrassed locals riding with him on their motorbikes.
The 'main road', Highway 27 is a good one to ride and not much traffic. Some of it is very new and different to map due to dam construction between Lac Lake and Krong No. Some is under construction, I had to push for short distances due to fresh unrideable gravel awaiting road roller, but nothing miuch.
On H27, there is decent accom at Krong No (aka Phi Di Ya) 43 kms from Lac Lake ( I stayed here to shorten next day). Then it is 72kms to Dinh Van a largish town, plenty of accom. Two reasonable climbs. I also saw basic accom in small town of Dam Rong 40 kms on from Krong No. So plenty of options to break up the journey.
From Dinh Van, I took the 725 to Dalat to avoid H 20 - good road and fairly quiet.
Hope this helps anyone doing it in the future.