Get a couple flamers for the ass-marines... use them better... and they are a solid choice...
I will play you using my Space Marines some time, and show you how they work better, or watch a couple games where others use them, and you will see.
30+ attacks on the charge, after some flamer and pistol action... is actually very brutal vs almost anything you face.... the key is to learn how to move 12... shoot... and still be in a good assault possition.
Cheers.