Sto aluminum or delrin

Didn't get a response from STO so I will ask you guys. Is there any advantage to the delrin end cap other than weight. I am looking at the falx high flow. I would assume the aluminum would be stronger. It is also not clear to me if you can unscrew the end on the aluminum one for future updates. They talk about the delrin one but didn't mention the aluminum one. Just want to be sure before ordering


 
I don’t have any experience with STO products. But I have some experience from a manufactures perspective with Delrin and aluminum. 
When wood is not durable enough but the part does not need to be made of metal. Delrin is an excellent choice. 
Delrin is easier to machine than aluminum. So machining cost should be less. 
Delrin does not require a coating such as anodizing or paint. So Cheaper manufacturing cost. 
In the end. Delrin components should be less expensive than the same parts made of aluminum. 
If a manufacturer offers the same part. One in Delrin and one in Aluminum. It is usually because some people feel the aluminum part will be superior to the plastic part.