Do growlers of different materials have a tangible impact on flavor? Most commonly I see glass growlers, but on various sites and at specialty shops I occasionally see variations: ones made of stainless steel or plastic for example. 

One would hope that there aren't too many negatives associated with these, but are there proven differences? Is it the same as a bottle vs. can, or does the (usually) limited time in the container make the material...immaterial?
The biggest impact tends to be the color of the container. Green and clear bottles let in more of the harmful light that spoils the beer. The darker the container, the better.

Plastic also lends itself to being scratched if re-used (which most growlers are). Even powdered cleaners with soft cloths can scratch the plastic (if the cleaner isn't disolved well enough) and make grooves where bacteria can sit and ruin future beers. 

While it isn't the only choice: Dark Colored, glass growlers that have an air-tight seal would be the best for longevity sake.