"poor college student" does not equal 5.7 caliber owner.
1. Ammunition is fairly expensive (However, prices have come down quite a bit for now)
2. They are not useful for anything (I have owned both Five-Seven and the PS90 for many years.....so I know).
3. When I bought these they were cheap.......then the price skyrocketed for some reason. I sold both because I made profit on both.
4. Factory magazines are expensive. However, I have not used the 5.7 upper mags sold by some AR upper manufacturer in this caliber. Also, when I bought mine, I could only get 30rd mags.....so I had to get 50rd conversion kit.
One advantage I know about these guns is very low recoil. I can unload PS90....all 50 rounds.....in 3 inch groups at 25 feet very fast. That is even with the horrible trigger of bull-pub design.
For Five-Seven, there really is no advantage. It is very large to carry. Capacity is claimed to be an advantage, but other full size guns now offer high capacity magazines that fit. Mild recoil is nice, but then 9mm recoil really isn't that bad.