The problem is to balance NPC attackers to pose a threat to newbies as well as well-prepared PvP'ers with PvP hardened ships... It's simply not possible... you can either balance NPCs for the weakest link in the chain (aka the newbie PvE only player) which is laughably easy to evade for experienced combat players, or for the combat hardened players, sentencing every one else to death.
I think it can be balanced using your combat rank and current ship. If I were FD, I would assign a "combat rating" to each pilot, ship, weapon, and engineering combo (like the "car rating" in the Forza games, something like that) and balance against that with a combo of ships that match that combat rating grand total. It's pretty easy to do.
Aside from that, there's the option of not balancing at all, as it should be in reality, but it's definetly less fun in the long run.
Yeah. It's gamey feeling to consider that there's trillions of square miles of rocks and somehow 1 or more pirates are exactly where you are. Sometimes it feels like Elite isn't an example of the empty void space, but rather the bathroom at a some busy airport.
A problem being attacked by pirates while collecting void opals is that there's a time limit to those rocks. Their life-percent goes down in a few minutes. Going away from them and chasing pirates might cause a problem collecting the minerals because they would be gone when you come back, so I hope they don't increase pirate activity for that reason.
Still, wouldn't want an increase in encounters. Would take away from the experience. Unless, just thinking, maybe the pirate activity would be a reason to do deep space mining, say 500 LY from bubble being safe, while in bubble it's not?
For me, pirate activity inside the rings and outside of interdictions is just a matter of realism and sound game design. With the current "gold rush" for deep core mining, there are countless oportunities to make money with piracy. And if I was a pirate, knowing that interdictions are easily avoidable, I would try to follow the miner into the ring and attack him when he is more vulnerable: in the mining process.
I find it gamey that there are ships spawned in your instance as soon as you drop, but I wouldn't mind having to fend off a couple of pirates each mining session. Loosing your ship and cargo from time to time is also a way of "enticing" players to do better next time. I can't remember the last time I lost a ship, it's been years ago. Maybe a 10% chance of spawning every 10 minutes?. Of course, if you're away from the bubble, chance of spawning would be reduced or even denied, as it would be in more secure systems. That would make us think twice where to mine... because right now, the best place to mine is "anywhere near the station with the 1,6mil price".