Well, we switched developers mid stream, and a ton of info did not make it from the old to the new developer.... thus, it was like starting over, without the ability to reference the prior version. Something as simple as looking up the old graphics for jobs, had we left the old system up on a separate server would have made this simple.... instead we have to reverse engineer most functions. Thus it is slow going.
Also, many functions were partly installed, but not completed, and there were bugs that came about as a result. Those had to be fixed as well.
There really were 3 reasons for the upgrade.
1. The old version is reached end of life status, and thus was no longer supported. Ie, if had security risks and patches were not available to fix them (initially, the patches just didn't work probably due to conflicts with hacks)
2. Many of the hacks and mods did not scale so well as the site grew, thus we kept running into database crashes. For the most part, much of that, but not all has been repaired.
3. Having a coder get up to speed on all of Erwin's customizations and make direct plug in updates could likely take a year, and yet for security, something needed to be done to address current vulnerabilities.
Thus the upgrade had to occur, but alas, in hindsight, it could have been handled in a much different fashion, but these were the cards we had to work with.
I really like that new jobs have been added!!! 
