There are Minsk parts along the border with VN in Laos but they dry up after Lao Bao/Dansavanh in the south. One reason that the Minsk is not as big in Laos and Cambodia is that better bikes abound. If you have a little mechanical skill, you can keep it running as long as you leave Hanoi with the parts you are not going to find in Laos or Cambodia. While I have a Minsk, it is not my riding bike as in Laos, the speed of bigger bikes and reliability is the issue. To be honest, I'm not sure I could find all the Honda or Suzuki parts I needed to repair a bike while on the road but know that I could get them sent from VTE to me in Laos and from PNH in Cambodia.
When you pay USD $ 400 - 600 for a bike, you can not expect it to run 5000 km in 4 countries without difficulty and then again some people are lucky and get by with no trouble.
Matt ran well with his Minsk but on average, he was a little more of a rider than those that rent the bikes in Hanoi and putter about.
If you do get a Minsk and ride in Laos from VN, you can call upon me for spare parts that you can't find. If I don't have them, I can get them but it takes time to have them sent by bus from Hanoi. Once in Laos, I can send them about the country easily. I once had the rings break apart on my Minsk and ruin the cylinder and get the fly wheel stuck. With a few phone calls, a replacement motor was onboard a bus heading my direction. Good thing the motor comes out with 4 bolts and a few pieces of wire to be removed, 20 minutes out and 20 minutes in.
Best to have the bike blessed as well, can't hurt.