Ravenna Grass - Saccharum ravennae - is very hardy here in Utah.
|Ravenna Grass in Sandy, Utah|
Pampas grass - Cortaderia selloana - in hardy in zone 7 or warmer (on the Wasatch Front, we are a zone 5 - 6; a little too cold in winter), but some varieties are hardy in zone 6.
|Pampas Grass in Sandy, Utah|
In other words, Ravenna Grass will definitely survive the winter here, and Pampas Grass might or might not.