Hey there.
If something has a reduced capacity for addiction, that means if someone was taking it is less likely to become addicted to it than something with a higher capacity for addiction.
Someone taking ER formulation oxycodone for pain is less likely to become addicted/dependant on the medication than someone taking the same medication in IR formulation. As I've explained, the reason for this is the consistent painkilling effect gained by a constant drug serum level. If you take IR meds every four hours and notice your pain creeping back after three hours, what will most people do? "Oh it's only an hour" and they'll take a pill. This builds a psychological link between taking the medicine early and the pain going away (and likely a 'buzz' due to slight overdose). Over time this means the 4 pills per day prescription has become an 8 pill per day habit.
Whereas ER medication, you take your pill at 9pm when you go to bed, you are asleep all night, you wake up with a bit of pain then at 9am on your way to work, you take your pill, constant pain relief for all that time, then when you get home and go to bed at 9pm, you take your pill, repeat ad nauseum. This means, due to the constant pain relief and non-fluctuating levels of pain, you are more likely to only take your pills as prescribed. Put it this way, I know a lot of pain management Doctors, some heads of the British Pain Society and they are all proponents of this method for both opioid-naive patients and opioid-dependant patients.
It works. The medication is the same, but the method of taking it and the pain relief gained from it in both methods of taking it are what makes the addiction potential different.
I am also a chronic pain patient, I take 240-300mg of oxycodone per day. This is in the form of:
2x OxyContin 120mg. (Still OCs, we don't get the new OPs in the UK).
2-3x OxyNorm 20mg.
I rarely, if ever, take the 20mg, maybe one or two a week if I am in stupendous pain due to falling over that just isn't going away or something, but I always take my OxyContin when I am supposed to and I get fantastic pain relief all day from it.
My point is this, if you take two people, both opioid-naive, in similar pain (on the pain chart and in the same place) that gain the same type of relief from 10mg of oxycodone and gave one 2x OxyContin 20mg per day and one 4x OxyNorm 10mg per day, the one taking the OxyNorm is more likely to become addicted/dependant on the medication. This was the case for me and many other patients of the Doctors I know. It's not just the medication, it's the method of administration, the consistency of pain relief and a whole host of psychological factors, but this is the reason why, especially in the UK, you may get prescribed MS Contin or something for pain relief, but the chances of you being prescribed IR opiates (besides codeine) are much, much slimmer and this has worked for us.
This is only when the medication is taken as prescribed, not factoring in abuse such as crushing the pills etc etc.
Tricomb:
I can say paracetamol is safe without any definitive studies on whether or not it is safe for one reason:
If 4g of paracetamol per day was causing noticeable liver damage, we would have seen it by now..
If you say that 0.000001% of the population of the Earth is in enough pain to take 4g of paracetamol all day, every day, that's 7000 people. That means every day, 7000 max paracetamol/days are passing. Given that they may have been taking it for 50 years, that is 126 million max paracetamol/days. Given a sample size like that (and I am sure it is actually much bigger), we would have seen trends appearing if that dosage of paracetamol was causing liver toxicity.
Of course, I can not be 100% certain, but given the information we have, it seems to be safe when taken as prescribed, which is a max 4g per day given a normal day for a healthy person.
It's been shown that your liver can handle 4g of paracetamol per day, and I'm certain I read a study that after 50 days/100 days or similar, they tested patients AST levels and they were unchanged and their liver was unchanged from the first week they started taking the paracetamol. Like I said above, given the amount of paracetamol days seen worldwide, statistically, we'd have seen something by now.
My statement is totally true, ER medication has a much lower capacity for addiction/dependence than the same IR medication, this is for the reasons I've explained above and many more. If you stay on either long enough, you will become addicted/dependant, but, if you are only taking it for a month or so, i.e. for post-surgical pain, then the person on it for a month on an ER regimen will be much less likely to suffer withdrawal and dependence issues when they stop the medication when compared to the person on the IR regimen.
Finally, go see your Doctor, and ask about an ER schedule with IR for 'breakthrough pain', but with a good ER schedule, you really shouldn't need IR medication.
Disclaimer: The number of paracetamol users above was just picked out of the air, but I think it's a lot more than that and the principle is sound. 
!