When Sansha's Nation launches an Incursion into a Low Security or Null Security constellation, Incursion rats frequently (but not always) camp the Stargates. These gatecamps will include a mix of ships that usually includes frigates that can microwarp 2.5 km/s. They all can, and will, targetlock and chase any player on-grid regardless of the distances involved, so if you appear 400 km off the gate, they will start running after you.
I've never seen Sansha gatecamps use smartbombs, so Covert Operations frigates can worry a little bit less about being smartbombed on Stargates (though I still don't advise warping to zero on any LowSec Stargate if you have non-blues in Local; a sufficiently large player gatecamp can deal with Sansha rats that show up, and Sansha gatecamps yield no rewards, so there isn't a reason to limit the size of a player gatecamp).
Non-CovOps non-frigates, however, are at considerable risk, as they may be destroyed by a Sansha gatecamp when emerging from a Stargate in Low Security. Slow frigates like rookie ships and other slow frigates may also be destroyed before they can align. I once saw an Apocalypse-class Amarrian battleship get eaten by Sanshas when emerging from the first Stargate into the Incursion area.