I, too have used deficits for getting from floor to knees and then rack pulls from knees to lock out.
I have a hard time getting off the floor (due to mobility and form) but with a deficit it's helping me getting more speed off the floor. IE: I can do 445x5 reg deads, or I can rack pull 605. It is also what works best for you. It's nice being on a forum like this so everyone can give what works for them and gives you some ideas to try.
You might also try deadlifts and really check your form to hopefully help you get where you want to be.