Was reading earlier about your thoughts on covers and i wanted to join in with my 2 cents.

How about when you fire on a cover with a Heavy flamer, the cover takes the brunt of the damage, while it continues to do damage behind it, but at 50% (degree to be determined later) effectiveness? That way the player have to chosse to move around the cover to deal full damage or fire through it and still maintain some effectivenss. 

I reckon this can also apply to some other weapons, thinking mostly of the meltagun-family and their channeled attacks.