Aluminum is soft, that's what it comes down to in the end . The plastic that is used is made to survive a lot of heat and pressure for years on end or the life of vehicle . It seems like the total opposite would be true.
You said you wanted to do it as precautionary maintenance , If you decide to get a new one , whether it's metal or plastic make sure you don't get the cheapest thing you can find. Get oem or something close to it. Last thing you want is a leak or it failing especially while driving.
These engines don't have any issues with there oil filter , caps or housing. The aluminum ones do have a couple major issues. The threads are easily damaged, since it's made from soft metal the housing it's self is easily damaged and it not uncommon for them to leak.
I was asked 2 times to do this swap. Since I didnt know anything about this part I asked a few Toyota mechanics I know. They all said the same exact thing, stay away from it. The plastic while OEM is a major upgrade compared to the aluminum.
I've also read on the forms people saying they where told by Toyota mechanics the same thing.
Thanks for the input. Its difficult for me to see the plastic being more durable than metal though. With that being said, I think I'll stick to the original plastic one unless it cracks or something.