Usually the seats that "eliminate the need for a riser" are about 7" higher comparing to regular ones (have a built in platform that elevates them).
Two things to remember:
1. Most risers that need to be built would need to be higher then 7", unless your screen is mounted very high off the ground or you just using a regular TV.
2. It is not very comfortable to get in and out from the seat that is 7" higher then the regular one.
Fusion Collection Seating
Ultimate Home Entertainment