I went by bus from Son La to DBP by bus when they were rebuilding the road and it was a sea of mud in places because it had been rained for a few days (it was April, not the wet season). Most of the 4 wheel drives turned back but the bus got through, with some help from mechanical diggers. It was very slow. I was tols at the time that the next section, toward Sapa, was a lot better, but it wasn't being rebuilt then.
Really, it will depend on rainfall I think. I wouldn't be so concerned by dust and bumps.
#2 violets has been a member since 6/7/2009. Posts: 152