This is really close to what you're looking for. (Destiny)
http://db.destinytracker.com/compare/
You can add items to a comparative chart at least; it looks like the functionality of the perks settings isn't totally built in, but may be in the future? Something to keep an eye on.
Complete thread:
- Dynamic Weapon Comparisons? -
Monochron,
2015-06-03, 01:54
![[*]](themes/default/images/complete_thread.png "Open whole thread")
- Dynamic Weapon Comparisons? - TheeChaos, 2015-06-03, 14:09
- This is really close to what you're looking for. - iconicbanana, 2015-06-03, 14:34