Yep, totally agree with this. Take it from someone who has spent the last 2 months on WotL: If you do not have a defined project plan from the very beginning, or if your project requires anything beyond what the most basic tools can do, stay away and plunk around on the PSX version.
If you DO have a defined project plan, and a good reason to go for WotL, it takes some finesse and compromise, but it is possible to do quite a lot with the tools that are readily available. Just get ready to curse out FFTactText on a regular basis.
My patch is 95% done, and I'm in the middle of test playing it, but I've seriously wondered if the extra classes, characters, and abilities are worth the headaches. When this is done, and I port my changes over to PSX, I have a feeling like I'm going to belly laugh with relief at how easy it is.