It's probably against our NDA to reveal anything too specific, let alone publish it.
From memory, there wasn't a great amount of real meat left out of what we playtested - more like a lot of variations on how to do stuff, see what worked for people, change what didn't for next time. In fact, all I can remember was variations that were changed, rather than anything specific that was actually left out. More the complete opposite, i.e. there were complete sections of rules that were never play-tested. For example the Warlock class was never in the playtest rules, nor were the final XP rules (an early version of XP and monster level was in the alpha/public beta, but it was changed heavily in final 5e), the encounter building rules were never in the playtest (no wonder they are a mess), and so on.
I do recall our Wizard player saying he was disappointed with how loads of people complained early on that Wizards were too powerful, so they got nerfed in the next playtest pack; I think the final way Cantrips scale has alleviated that problem somewhat, but I do still agree that while the baseline for Wizard in 5e is better than it was for say 3.5, the general damage output is still too low for most spells (a high level spell should be far more significant than what someone can achieve by using a weapon for a round).
From memory, there wasn't a great amount of real meat left out of what we playtested - more like a lot of variations on how to do stuff, see what worked for people, change what didn't for next time. In fact, all I can remember was variations that were changed, rather than anything specific that was actually left out. More the complete opposite, i.e. there were complete sections of rules that were never play-tested. For example the Warlock class was never in the playtest rules, nor were the final XP rules (an early version of XP and monster level was in the alpha/public beta, but it was changed heavily in final 5e), the encounter building rules were never in the playtest (no wonder they are a mess), and so on.
I do recall our Wizard player saying he was disappointed with how loads of people complained early on that Wizards were too powerful, so they got nerfed in the next playtest pack; I think the final way Cantrips scale has alleviated that problem somewhat, but I do still agree that while the baseline for Wizard in 5e is better than it was for say 3.5, the general damage output is still too low for most spells (a high level spell should be far more significant than what someone can achieve by using a weapon for a round).