To be honest, there are better people on here to comment about handling.
But I'll add what I can. looking at the front of the car, think of the chassis as a box.
The two strut towers are the sides of the box and the subframe is the bottom.
I can see the use in adding the upper strut brace as this would complete the box if see what I mean.
As for the lower brace, I'm not sure how much effect it will have as it sits a little way in front of the box section of the subframe.
Personally I won't be fitting either as I haven't felt the need to as I don't seem to run my car to its limits on my daily drive.
If I attended track meets, then it would probably be a different story.
Anyways, heres where I as for Ess_three to comment.