The original 400 damage each second for 8 seconds should be restored.
it should be upped to at least 600/s because the original set had 8 sec duration 8 sec cooldown, unlike now which it is 8 sec duration 16 sec cooldown.
This set really needs to have its 100% uptime restored and to get an upgrade in its debuffs since they are both now so a) common, b) under-powered.
I like two different combinations:
1. Minor Defile and MAJOR Defile (awesome for PvP though still useless for PvE).
2. Minor Breach and Minor Mangle (awesome for PvP and trash-pulls in PvE - also useful if you don't want to use Pierce Armor for whatever reason on some exotic tank build).
To 'compensate' I would just drop the damage component of this set entirely. It doesn't move the needle and steals away 'power budget' that can be used for better aspects of the set.