I am going to Vietnam end of February together with my girlfriend for 3 weeks. 
We want to rent a motorbike for part of the travel (Hoi An to HCMC). We will both ride on one, for this, and because we do want to avoid breakdowns, we want to rent instead of buying the classic but said-to-be-unreliable Chinese Honda Win. 

I am a motorbike rider in Germany and I feel like getting a manual instead of a scooter or so. 

One renting company suggested the following bikes: 

If a regular bike: 

* Lifan CB 150 cc
* Honda FT 230 cc

If I wanted Enduro Bikes: 

* Honda XR 250 cc
* Honda XR 150 cc

The Street bikes are generally cheaper and maybe more comfy for two persons, the enduros seem to be more suited for the roads to expect...

Does anybody have experience with those bikes?

What do you think about the road conditions and having a street- vs . an enduro bike down in Vietnam? 

Any other tipps?
Thanks a lot.