Would you recommend cutting back Stipa grass in spring in order to encourage new growth.
I doubt whether cutting grasses down in Spring would actually stimulate growth, in the same kind of way that pruning stimulates roses.
Personally I prefer to leave grasses untouched through the Winter. They can look very attractive when frosted. That's part of the appeal of growing grasses, to add all-year-interest to a garden. They can also help to provide a habitat for insects.
Givng the plants a haircut, removing the dead material in early Spring, will help to give the plant a lighter and more fluffy appearance when it grows. A helping of general fertiliser, applied in Spring, will also help.