Honestly it's the luck of the draw with crank failure. I've seen banshee's with pipes and filters have the crank come apart, and I've seen ported banshee's not have an issue.
I had mine welded for the piece of mind, and IMO is well worth it.
So to answer your question, do you "need" it welded.....probably not. Will you have issues....you never know until it's too late
-Zach