Well I think the gearbox is not good even people keep saying it. I have read and heard so many who have been left with the problem the few first gears are not working and dealer or hyundai say it working properly. 20k behind and not really happy with the car anymore.
This is subject to personal preference and experience with faulty gearbox's. If it were a recurring mass problem, there would have been a recall notice by now. the vast majority of owners would speak the opposite to "what you have read". If the cars with suspected faulty synchro's went in for a gear cable adjustment, I would imagine a large number of synchro's would not have had to have been changed as part of the problem has been poor gear selector cable adjustment from factory.
You are focusing on a small minority of negatives against a large majority of positives. The gearbox IS a good gearbox, and is better than a lot of cars I have driven, especially the latest civic type R for example. It's well known it's not a bad gearbox; It's partly known occasional issues that poor investigation has led to just replacing parts that may never have had to be replaced.