In regards feats/ability upgrades; I say they are 'progression picks', meaning you sacrifice sub feature+save/skill proficiency pick in upgrade in return getting progression stuff. Example if you take only progression stuff as fighter you get all extra attacks and ability/feats fighter gets but nothing else (besides 1st level stuff). So with caster progression system also gives feats/stat increase from other class besides increase on spell slots.<br/><br/>In regards subfeatures, you can pick earlier subfeature if you so desire (example in second other class increase and going tier 3 you can pick stuff on tier 2). You get for free archetype stuff in 3th level (or other 'defining feature' in 3th level). Example sorcerers get metamagic options in 3th level and they come for free in tier upgrade. So going to tier 2 you get lot of stuff but after that it goes to cherry picking then.