Wow. I've been using T3's T3s's and ProTanks for over six months and I've never had that happen. Even when a top wick was insufficient and the thing was gurgling - still not leaking out the bottom or flooding. I always use them with the OEM wick in place - 2 pieces of wick. They really don't survive long - some times even one cleaning - so be prepared to replace them. Either with more silica wick if you have it. Or you can "McGyver" some rolled up cotton cheesecloth into a replacement wick. (It actually works quite well as top wick material.)
Are ya sure the thing was screwed all the way down properly? It's about the only thing I can think of that would allow the contents of the tank to completely flood out.
The only other possibility is the PT/Evod heads are slightly different than the T3s heads. Was it the right head? Right below the wick, there is that flat circular piece of metal (looks like a washer) that has an o-ring underneath it. That metal washer is larger on a PT head than it is on a T3s head. Because of that difference, trying to use a PT head in a T3s base might prevent that o-ring from making a proper seal.