Fair point if you have a high speed connection. But if your system overheats during decompression, the fault lies with your shitty technical skills instead of the repack. Clean your rig, man.
The compression was already explained - I would add that if you’re not deep into scene groups, popular repackers are in general a safe choice, i.e. no malware included. Of course it’s never 100% safe, but in my opinion safer than picking from a list of torrents what could be the scene release.
I never had issues with fitgirl and Dodi, maybe other users can drop some more names that have proven to be reliable over a long time.
Nice feature. Is it reliable? I can imagine this being dangerous if someone finds out how to manipulate it to flag a malicious site as official.