It has seemed evident that the Order would rather capture than kill - especially Harry - as he himself says in the Battle of Seven Potters. So, it is safe to assume that all the Death Eaters will always be given a chance to live. And given the answers in Neville's case - it seems that Neville was expected to survive at least the first attack.
Now - in Goblet of Fire - Barty Crouch jr exclaims:
"Tell me he told them that I, I alone remained faithful... prepared to risk everything to deliver him the one thing he wanted above all... you"
On another occasion - in Half-Blood Prince - in Spinner's End - Bellatrix claims that she would've given up her sons for the service of the Dark Lord
"You should be proud!" said Bellatrix ruthlessly. "If I had sons, I would be glad to give them up to the service of the Dark Lord"
Assuming the same ruthlessness will hold true for herself rather than her sons - If Bellatrix - or Barty Crouch jr - had sacrificed themselves for the Dark Lord's cause - would he have survived?
Specifically - Does the nature of a person's sacrifice affect the protection? Will sacrifice out of fear or dedication to their master provide a similar protective shield - even if it might be weaker?