>>535328324
Say you have a mon with 100 SPD, facing an enemy with 700 SPD. In OG CS, assuming the enemy only uses skills with normal cooldown, it'll act 7 times before you can act once. With the changes introduced in Hacker's Memory/Complete Edition, those become 300 SPD and 900 SPD, so you're only being outsped 3 times instead of 7. It's only ever a hinderance if you outspeed the enemy to begin with, which usually doesn't happen where it matters. It helps make a lot of Digimon more viable to use, enough that something like Great Challenge 2 Duftmon dies to teams like this, or similar.
>>535328602
Yeah, for the most part, Hard Mode on CS (whether OG or Complete) usually bumps up enemy HP, ATK, INT if they're a mage, and SPD, while reducing their DEF, INT, or both, to encourage use of regular damage skills.