You've had a lot of good advice here, and mainly I just wanted to elaborate on a few things.
First of all strings break from three different basic reasons.
The first is from mishits, where the ball is struck near the side or head of the frame, causing a sudden jarring impact at an area of the string that is not able to expand like it would have near the sweet spot.
A second, fairly rare, but worth checking on your brother's frame, is that the grommets have been damaged, and have some place where they have a sharp edge that is cutting into the string.
And the third reason for string breakage is that the mains and crosses saw against each other with each hit, so that eventually over time the string is so thin at the cross points that the string breaks.
This sawing is accentuated when you have a firmer string like your Luxilon sawing against a softer string like your VS gut. So that is why several are amazed your strings are lasting 2 1/2 months. And realistically, although you may be hitting the ball pretty hard, you can not be bashing it near as hard as those whose hybrid string life is measured in hours.
String savers work to prevent the sawing of the two strings against each other where they cross. They do extend the life of string, but as you are already getting beyond the usual expectation from playing without string savers, they may not be worth it to you. First of all, the Luxilon poly's lose their tension over time, so it may be a good idea to replace your string anyway. Second, you would have to use a lot of string savers all over your hitting area to prolong the life of the string, and this changes the feel/performance somewhat of your stringbed.
As time goes by, you are going to become aware of any poly's tendency to lose tension and "go dead". How quickly it "goes dead" is dependent on how hard you hit the ball. In a hybrid with gut, this tendency is disguised somewhat, because the gut does not lose it's tension very much, and so you are using/feeling the gut in your stringbed more as time goes by. Now that you are aware of this, you may notice it more, but it likely is a very slow process in your hands.
There are other gut strings out there, but virtually everybody considers VS the best. (I use Klip armour pro in part to save a little money, and because in a hybrid I can't tell a huge difference from VS except that it is a little "stiffer" which I like because I don't have to string quite as high above my frame recommendations.)
And finally, between you and your brother you seriously ought to think about getting a stringer. The strings are much less if you do it yourself, and you can experiment a little more with your string choices and tensions.