You cycled in V!etnam? Great country, but HCM takes some guts. Mind you, so would the road between Da Nang and Hué, if for other reasons.
By the way, my touring bike there was a Brompton - 6 gears only, so, to the OP, yes 5 gears can be fine, depending on the terrain.*
To those non-UK habitants, do bear in mind that Dawes has a good name in the UK and is reasonably common. As to cycling in France, there's a good mixture of mountains, river valleys, bike paths and, of course, quiet roads with usually good support for cyclists not too far away. 5 gears should be fine for a lot of the country, depending on where you want to go.*