The problem with ripping a guy's face off is that while you're doing that, all his buddies are at pointblank range, and emptying their guns into you. Vanilla SRM troops may do middling-to-respectable damage, but there are plenty of platoons out there that will shred a battlesuit squad that gets in that close in only a couple salvos, and if there's more than one platoon around, they can do it in a single turn. Much like Clan 'mechs against IS ones, you can kill a lot of them, but only if you do it smart.
The secret to using a single Star to kill an entire company is to make sure that whole company can't shoot you at once, with the less enemy shooters at a time, the better. Similarly, if you want to use a Star of Elementals to wipe out an infantry battalion, keep the number of platoons that can shoot back at you to a minimum. Use your SRMs on a couple platoons to hurt them hard and degrade the damage they can do in return. After that, keep moving and try to engage a single platoon at your long range. You won't hit all the time, but between the range and your movement modifiers, they'll hopefully hit less. Remember that unless you play Hell's Horses, conventional infantry are totally outside Zellbrigen, so there's nothing wrong with focusing a full Star of suits on a single platoon to quickly wipe it out.
If you're facing the rapidly-growing number of infantry types that can actually outrange Elementals, try to use cover and avoid LOs until you can suddenly jump to pointblank range, and try to wipe them out in one blow. This is especially true against troops with field guns.
Now if you find yourself facing field artillery, or Stone's Trackers...bite the bullet, and call in your own artillery or air support. Anyone who's seen their record sheets will agree that you've lost no honor in doing so, and trying to take them on directly WILL get you slaughtered.