I'd splash down for a new bike considering you're planning on at least 4 months of touring or at least think about a better used one. The folder you linked doesn't seem to be designed for air travel especially, I don't think it would fit in an airline 'legal' case. GT's are OK but AFAIK a mass-market brand aimed at casual riders so components may not be esp robust. You could buy a nice used old-style non-suspension MTB frame & put on a mix of good new/used parts; lots of folks who favor flat-bars do that. Tourists seem to favor canti brakes over V-brake, both can work well.