Its not just flying qualites. Qual evals at Test Pilot Schools are a good way to look at flying qualities, performance, and systems on some pretty unique aircraft. Which aircraft TPS uses all varies based on money available and what's available that can be put under contract (most of these aircraft are on the airshow circuit). For military aircraft, TPS horse trades qual eval sorties with flight test organizations around the world to get the students to fly unique military aircraft. The idea is that you're handed the POH/dash one/NATOPS/other aircraft manual, you then build test cards to test certain aspects of the vehicle. Finally, you report on your flight noting the good / bad items you found and translating that into how the vehicle can / cannot accomplish its mission. It certainly is not "here, don't crash it!" Every sortie I flew was with an IP/CFI. Each qual eval represented at least 10 hours of prep and report writing for every hour flown. For all the taxpayers in the forum: Its a good deal, but its definately not "Hop in! Let's go fly!" on the government's dime. 
 
Here's a list of the aircraft I got to fly at TPS:
Trainers:
C-172 G-1000
T-6A (new one)
T-6 (old one)
T-37
T-38 A/B/C
T-43 (737-300)
T-1
SK-60 (Swedish T-37-like primary trainer)
 
Fighters:
F-15 D/E
F-16
NF-16  (TPS-owned variable stability F-16)
F/A-18F
 
Utility:
HU-16
AN-2
C-12 (King Air 350)
NASA G-III 
U-6 (DHC-2 Beaver)
LJ-23
 
Helos:
UH-60
 
Gliders / Airships:
Good Year Blimp
L-13
ASK-21
Grob 103