Seems to me you have answered your own question?
Haven't used either, but you can't go past the support available on the forum for Amibroker.
Bit like buying a new cheap car with the dealer being miles away, after sales support /warranty is hard and time consuming?
However, there may be another forum active for Insight Trader, there's a forum or multiples of, for everything these days!
Is it active though?
Best of all, the support here is FREE... !