I think the 1500mg of BO a day is a good place to start. I remember reading about others who tried extra pills, but lost all their aches; as soon as they went back down to the lower does, the aches came back. I had tried that a few times myself. Last week, I tried taking 2 BB pills in the morning and evening, instead of 1; and then I took 2 in the evening only for a couple more days; and I really had no pains during that time. As soon as I just backed off to my usual 1 pill twice a day, I started feeling pinches and aches again. Also, a few months ago, I bought some BO from Swanson's to add to my BB pills (one extra BO pill twice a day) to see if that made any difference, and I lost pains during that time. And again, just sticking to the original 2 pills a day brought the pains back. So your 1500mg is a good place to start. If you don't feel anything going on after a few weeks, try ramping it up to 2000mg. Or try taking it down to 1000mg. Eventually you'll find a dose that works for you! Since you're already having pains, the 1500mg will probably work just fine for you.
I personally only take 4000mg of MSM cuz I can't stand the thought of swallowing another MSM pill! They're HUGE!!!
The label on the bottle says to take three to five pills a day (each one is 1000mg), so I choke down four. I'm not sure what effects 8000mg would have ... ???
I don't know a lot about MSM long-term.
Sounds to me like you're off to a great start!
Oh, and Periwinkle - You're welcome!