I'm 46 datacards away from earning the Hard mode Max box. Here is my feedback on hard mode.
1) Diversity - I realize that the teams are randomly generated, but it would be nice to fight some stupid compositions for fun. Where is my Ima-Gun-Di led GR, Lobot led Droids, or Gar Saxon troopers?
2) GR Special Bonus - Because of this bonus, I try to actively avoid fighting GR teams. Maybe reduce the reflection to 50%.
3) Jawa Scavengers - Hard mode did a better job than normal mode about making each Sector Jawa feel unique in its offerings. My biggest and most controversial suggestion is to change the final Sector's offering from the R8 Injector Piece to the R8 Aeromagnifier and keep the steep price tag. This will force players to choose between those pieces, Razor Crest shards, or large quantities of G12+ gear or signal data.
4) Once a node has been 3 starred, make an option to turn off the bonuses/data cards on that node. This would allow players to test out compositions in situations closer to live situations. It still has an energy cost associated with it which might encourage some players to spend energy on the refreshes to test out compositions.
Overall, I do enjoy hard mode and have enjoyed the challenge it presents. As I said above, I would just like to see some more diversity or at least one crazy/fun team per zone, but it is definitely more fun than Grand Arena to me.