Well, I like to keep decent ratios (usually 3), which would keep my asymmetric home connection too busy - whereas my cheap VPS can do 1Gpbs (burst). And in my experience, the Pi doesn't handle well heavy random IO over the USB/ethernet bus - I had downloads with 20-40% of blocks corrupted upon verification.

And of course, while I don't consider it a problem where I live, removing the torrenting from your connection to a VPS in the Netherlands reduces the chances of having legal problems.

And the VPS isn't a dedicated seedbox - I'd still use it for my email server (Spamhaus' PBL prevents me from sending from my home connection), Tiny Tiny RSS hosting, website hosting, etc.