They don't die faster than pretty much any other infantry. So, like pretty much any other infantry, don't charge with them. It's not so fucking hard. And the losing 25% DPS per model is no argument, it's the same for any other SMG squad and noone's crying about them.
It's been said before, they are just not cost-effective. I use them very occasionally on urban maps to discourage flanks, but Grens perform that role almost as well and there is much less risk involved.