Having sat in the Jumpseat for direct entry First Officers and Cadet First Officers, I can tell you that once in the right hand seat of the jet, both types of pilots under training make similar mistakes (descent management, flare...) and are proficient in similar areas (SOPs, aircraft systems...) The notion that spending 5000 hrs flying GA/regional before jumping in an Airbus will be a massive advantage is completely false as the operating environments are vastly different. The 100+ pilots on the seniority list who started at Jetstar as cadets and are now in a fanatic career position. Why would you not join an airline in your early 20's and earn up to $200,000 a year?