They would have to change the sigils so that they have a 10 second CD.
I've been experimenting with a rapid endurance build that is just crazy fun and great survivability (I can easily kite packs of level 80 mobs forever without taking a hit), and the sigil that gives 50% endurance on weapon-swap (Sigil of Superior Energy) would be icing on the cake.
Here's my PvE build (still rolling with awesome 4 kits):
(I realize the 50%+ trait doesn't stack with Vigor, but I've decided it's still worth to have when Vigor isn't up)
Also, Rune of the Adventure (http://wiki.guildwar...f_the_Adventure) is incredibly good for endurance build engineers. When you swap to Med Kit that counts as activating the healing proc, and obviously Med Kit has no CD (other than 1 second swap-CD). I have noticed that the tool-tip is wrong for this rune, it's not a 10 second CD for endurance but 15 seconds. Still great though. TLDR: Every 15 seconds you can have full Endurance regeneration.
Edited by Zenh, 04 September 2012 - 06:37 PM.