Hi Hendi
I took a look at the link that you posted. H-C Travel is a tour agency that is UK based. They subcontract out the tour to a local operator.
The tour that is described on the link probably happened quite a while ago. The leader that is mentioned, Walter, totally quit the business a few years back and sold off the bikes. You might ask H-C Travel about that.
I would suggest that you find out who in Chiang Mai will be actually doing the tour, and ask for some feedback on them. You should also confirm that your bike will be 100% legally registered in Thailand, and that the tour operator will give you a guarantee that you will be allowed into Laos. Some recent tours have been turned back at the border due to lack of registrations and paperwork.
Walter's bikes were all legally registered. I don't know of any tour company in Chiang Mai that can say the same.
In-country tours can usually get away with unregistered bikes. Crossing borders is a different story.
BobS
"The true secret of giving advice is, after you have honestly given it, to be perfectly indifferent whether it is taken or not and never persist in trying to set people right."