The Matrix Radix 7 shaft weighs in the range of 69 grams to 73 grams and has a high spin rate. It also conforms to a mid launch. The Matrix Radix 7 shaft is more recommended for golfers that already have the launch angle they're looking for. The shaft itself is not considered to be a lightweight shaft, so distance will more than likely not improve; however, you can expect increased accuracy and stability.
The Matrix Radix HD uses the HD design derived from the Matrix HD shafts. What that means to the golfer is a longer lifespan of the shaft, and more consistency with each swing.
This shaft is not recommended for senior or lady golfers (try the HD Radix 5 or HD Radix 4).