(All my opinion)
You have two sides of cargo.. The "majors" like FedEx, UPS, DHL, ABEX, Polar and Atlas and you have "regionals" like Mountain Air Cargo, Baron, AirNet, Flight Express and Ameriflight. In the Past ABEX has furloughed and so has Polar. But to the best of my knowledge FedEx has not. UPS was threatining to earlier in the year, and that is normally a scare tactic used my management. UPS wanted an X% increase in pay, UPS management is saying we'll give you that but we'll furlough 100+. The "regional" 135/125 companies have been fairly secure, especially for your first step up. Baron and MAC have a nice security by being feeders for FedEx. They can use them to fly into smaller airports or airports where its not cost effective to fly a 727 into. FedEx also has security by the way of having a contract to fly the US mail. They are also the part of the english lingo... You dont say, i am going to overnight you a package, you say, i am going to FedEx you a package... same kind of thing like, how many people say tissues.. no, you say, hand me a Kleenex.
The check hauling companies like AirNet and Flight Express, have done really well in the past, and are currently still hiring. AirNet is projecting another 30 people for the year. These two companies have been sucessful thru the banks needing them, to deliver within a certain time period. But the future of check flying is changing. Quite a few banks, and customers do "online" banking. But even these companies have looked into other areas, breaking out into the Fractionals, doing isotope, or lab corp runs, or even doing charter work for electronic companies.
I have heard of flight express laying off a few people lately, and i think that was due to a base closure. The set back with a small 135 company is most of them dont have a furlough clause, so when they dont need you, they lay you off. For now, i chose, and was very lucky to become part of the cargo world. My opinion is when things go bad for a few years, it always seems that the cargo business bounces back quicker.