You will have just as many errors if not more by rolling back to an incompatible version. VaultWiki 3 is no longer under active development and will not even receive security patches after another 2 months. Simply put most bugs you encounter in version 3 will probably never be fixed.
All of the modifications I've made have been merged into the next update, so you won't have an issue of not being upgrade-able. Most of the serious issues you've encountered have mainly just been that some of the data was not transferred over.
Transferring data from VW3 was a one-time thing, not something you will be doing all the time. I only wish that we had encountered all of these issues in a staging area rather than on the live site. It would have been really simple to just copy the VW4 tables from a staging area once all the data was confirmed.
Many sites that started on version 4 have been using 4 for the better part of a year and without encountering an issue. I am confident that once things settle down, you will be pleased with the freedom and ease of use in many aspects that it provides over version 3.