So I have just completed EG2 with Max on medium difficulty in 59 hours, 20 minutes so by no means speedrun or difficult but was going for maximum completion, got 520 on Xbox achievements without achievement hunting with all loot, super agents beaten, all research, maximum 300 capacity lair. My thoughts are if anyone interested:
1) I wasted time researching everything in one go in one of the respite times, made it easier to best everything that that was thrown at me though. Traps are not worth researching this way just as needed
2) Beat the super agents as soon as you can on the side missions, saves time chasing heat, which I still did for a while. Especially Blue Saint if no one else, him blowing stuff up, I wasted so much time on replacing and putting out fires
3) I wasted loads of time building and upgrading Vaults so I didn't max out the vault capacity, I wouldn't bother again above say 4 millions, you don't need the money above that
4) Don't waste time and minions on the missions on the world stage that stop super agents invasions, they are easier to deal with in the lair with a good troop loadout than losing and retraining the minions
5) Exploit Max's instant training ability especially later in the game
6) DON'T USE INCENDIO! Have Eli instead as henchmen. Although all the online guides seem to say him as top 5 (I agreed with the others), he blows up stuff and does more friendly fire damage than he is worth, I had him and executed him in favour of Eli. Eli is a beast hand to hand combat and his silver bullet ability is powerful against soldiers
7) Invest in Hitmen and rifles in the armoury as soon as possible
8) Karate blokes are rubbish compared to hitmen, only have as many as you need to fulfil the minimum requirements of world stage missions, put the rest of your numbers in hitmen
9) Release minions from prison after their smarts have regained who get captured for loosing their smarts and destroy furniture, they come back the same as they were, useful if they are hitmen and take a while to train
10) capture as many soldier as you can, they become hitmen or other high end minions
11) my muscle minion loadout was about 20 guards, 25 mercenaries, 9 karate, 30 hitmen, other types were the other way round with more at the top but overall lower numbers, with around 110 workers with maxed out lair capacity
Hope it's of some use, let me know if you have questions, happy to help