All the above is good info, and would not argue any of the points it is up to YOU,
After a crash I have set up the system on the bench worked all componets, servo's I test by holding them in a vice and using a hook and line with weights, operated them but if I have any doughts I just replace them. never used a crashed 72mhs reciver, but with the new 2.4's I will have to waite and see.
One additional thing servs do ware out, not only the gears but the moters can get week, so you have to be the final judge
cheers Bob t