I have a naturally occurring axolotl morph and the biggest surprise throughout the process was the lack of stress shown. My axolotl continued to eat daily and shown normal behavior. She's about to be 3 soon and seems very happy and healthy.
I think the stress people associate is due to poor conditions prior to metamorphosis, or improper care during and after metamorphosis.
I can't speak for wikipedia but the two members who have replied to you have had first hand experience with artificially morphed axolotls, along with metamorphosed andersoni and tigrinum if memory serves me correctly. Ian was the first person I reached out to for advice when I was dealing with my morph. They are both quite knowledgeable on the subject.