In my opinion it would be an error, I love to play frontline even because if I lose I'll get somewhat and I can go on with my PvP rank, I didn't waster 20 mins of my life XD

I like the suggestion to base the reward on contribution, but not only on kills.
If all the places (1st, 2nd, 3rd) would have a lower reward than the actual (obviously higher for 1st, lower for 3rd), and then u will get a valutation like with the FATEs, it will be great.
This should avoid people that stay afk because the will receive a really low reward, and killer that would only follow and kill one by one player in order to obtain an higher final reward based on Kills.