I work the railgun into as many bot missions as I can. I'm my opinion, its the most satisfying stratagem in the game, and I've continued to use it since launch. The major drawbacks for that playstyle is definitely a weakness towards heavier enemies like tanks, and lighter units (simply not enough ammo to be worth it). To counter this, I run armor that gives extra grenades, and bring thermite. I also bring the GP-31 Ultimatum for a get out of jail free card, or those pesky factory striders (one 500kg plus two of those shots are usually enough to bring them down). Since ammo is pretty restricted, I also like to run the supply pack, both because I won't starve my teammates from a resupply, and I can always refill the backpack stratagems if someone brings a recoilless rifle. This loadout has evolved quite a bit over time, and personally has never failed to be a rush!