I do need to point out that after dumping something out of a Land Raider far from it's target, you've typically made back points no matter how quickly they kill you afterwards.
Having said that, the unit simply doesn't kill tanks fast enough.
I've dropped the poor scourges, and I'm instead putting in two units of Dark Lance Trueborn (3x model units) and a Ravager with Darklances and a Night Shield. I'm hoping that the extra DLs (and yes, I KNOW the Trueborn are extremely fragile) and re-upping to the Quad Gun will help me better weather the turn 1 storm. Right now, I simply find myself unable to kill transports fast enough to start shooting the meat. Once units are disembarked, I typically find it rather easy to mop up with all the poison and Psychic shenanigans.