The only joint pain I've ever experienced has been with doing Max-OT. Personally, I don't think it was b/c of the high weights and low reps, it was b/c of the 'loose form' they suggest that you use. Said another way, the joint pain was a result of too much force, not too much weight.
Since Force = Mass x Acceleration, you could potentially do more damage to joints by lifting lighter weights with 'loose' or explosive form than you could by lifting heavier weights under complete control.
Unfortunately - and this is totally my fault - I kept using that 'loose' form when I did my first 2 cycles of HST. I'm off this week from lifting (SD), but during the 2 week block of negatives from the cycle I just finished, I mixed up negatives with finding out what my maxes were using a much more controlled form and slower cadence, and that's what I'll be using when I start back up next week.
As far as the 15's go, I didn't dislike them, I guess I just wasn't completely sure of their value. I'm not new to training, and was already used to heavy loads from doing Max-OT for almost a year, so to me all they did was provide the expected 'pump' that high reps sets produce. I'm going to drop them for this next cycle and see how it goes.
I'm still not sure what kind of rep sequence I should do though. I'm not sure I'd want to do a 6 week cycle and then SD. The 2 cycles I've done so far I still felt ok after 6 weeks. It's been at the end of the 8th week where it starts to feel like it's time for a break. But who knows - since I'm going to lift in a more controlled manner with less momentum this time, maybe my body will feel differently after 6 weeks. Guess I won't know until then.