I just checked my video game playthrough spreadsheet (everyone has one, right? I'm not weird!) and I last played SS2 to completion in 2013. I played then on Hard and I don't remember it being difficult, so I think voodoo47 is right.
Well, I don't have a spreadsheet, but in order to keep record of my previous playthroughs I keep all my old savegames.
So, is the difference between Medium and Hard setting not that big ? If so I might try it on Hard the next time i play SS2. I've always played it on Medium and think it offers the right amount of challenge without being too frustrating.
It's been a few years for me, and I haven't made time for that 2017 playthrough (yet!), so I'm a bit rusty. Basically, everything gets a little more expensive. According to this FAQ on Gamefaqs by C.LE: https://www.gamefaqs.com/pc/185706-system-shock-2/faqs/41882
"On Hard, cybernetic module costs are 139% of Normal, rounding down.
Maximum HP is 24 + 3 x Endurance. Maximum PSI Points is 3 + 8 x PSI.
Replicator prices are 125% of Normal. In addition, enemies have a
30% chance of not even checking their loot tables upon death. "
I think if you've played and beaten the game on Normal, you should give it a go on Hard.