Thanks for the replies
I took my time to read some more online and this topic keeps rising from the dead every year it seems.
In India, since the "good" bike availability started with 700c, there are no options to get an older wheelset or an older 26" MTB. Also, it's not common to build up one's bike here so availability of rims/wheels is otherwise limited regardless of the size (can't forget the super high import duties) - just cheaper to buy the complete bike. I spent some time trying to find a 26-wheel locally but they're mainly available from local manufacturers so the quality is a question. same goes for the tires.
I do read in journals that Troll can be made to work with 700c and 27.5 wheels as well, but I wouldn't want to invest in the frame to start with an incompatible size.
Troll is interesting because of the rim/disc switch compatibility - but buying decision is currently on hold.
