I had purchased the blue metal version of this part to put in my Prophecy, and purchased this plastic version for my Retaliator. Even with the medium length (orange) worker kit installed, it is completely sturdy, and the air seal remains uncompromised.
If you plan on being very rough on your blasters or switching barrels frequently I would go with the aluminium version, but for everyday use the plastic version saves you some money that could be spent on a more important part.