I tried Zephyr and it is truly an Amazing tweak.....but I couldn't use because it breaks MiltiCleaner. And MultiCleaner offers way more functionality.
IMO....I think I have multitasking in iOS setup perfect.
I use:
MultiCleaner
Backgrounder
Multifl0w
And I love it.
I really wish i could use Zephyr but I just can't give up MultiCleaner for anything. lol