I agree with Music. I liked my crew cab 5.5' bed truck and had very few times when I missed my prior 6.5' bed truck. Crew cab 5.5' fits in my garage. GM/Ford already had the higher crew cab payloads and does appear to increase by about 300 pounds, making them very competitive with Ford's Max trailer towing package payloads. GM is following what Ford did for 2006-2010 F150s, though. Same GVWR for 5.5' and 6.5' bed crew cabs, means less payload for the longer beds.
Has GM put the SUVs on a diet too? 3-400 pounds more standard payload on the 1500's means maybe there is no need for a 3/4 ton Burb. The 2014 5.3L makes the same power as my 6.0L, while getting much better fuel economy.