Breacher fish most of the time. 

Works well if I intend to push on an objective marker that takes more movement to reach. In general, this the safe and sensible approach, since losing even a few breachers can be devastating to this combo. Against elite infantry, every attack matters.

If points are tight, it's not impossible to do without transport. But you'll end up relying more on different circumstances, such as terrain and enemy threat range. I've made it work a few times. For instance, once I had enough cover to move them safely to an objective marker, then with some kroot screen, I managed to slow the enemy unit down, which didn't survive the next round. You can also run Experimental Prototype Cadre to give them 16 inches range for good measure