ive always been a fan of the live walls but they do effect performance and battery, to be honest i havent found a LWP that i like enough to have it running all the time (can only stare at those nexus lines so long before i wanna run out of the "neural network")
Inspire is a very snappy phone and preforms well, but when you have a lwp you can definitely see the lag (especially when scrolling home screens and the app drawer.
as for the battery if i had to estimate a LWP probably knocks off at least a half hour/45 minutes
the decision is your preference if you want from over function, use a LWP.
i think their more of a gimmick than anything, a feature thats nice to have but not necessary