It looks like a sound program, Big. However, your starting weights on the 15's seem a little light. I normally try to keep the starting weights within about 70% of my 15 RM. Less than that and they don't seem too effective. Your other increments seem fine. My only other small suggestion would be to switch the flat bench to either an incline bench or weighted dips as they hit the pecs a bit more effectively.
One set for the 15s is fine. This is because you are looking to do 10 to 20 reps for each lift. So then when you get to 10s you can do two sets (20 reps) and in the 5s two sets (10 reps)
If you had done 2 sets in the 15s you would have 30 reps and this could throw the progression off a little. Yes it was less weight ---but at 30 reps that is a lot of time under tension. And it would be hard to do 30 reps in the 5s. Remember in the 5s you will want to do some burn sets. To keep the metobolic stimulus going.
From the iron you are throwing around you obviously are not a beginner. However I would stick to vanilla HST for 3 or 4 cycles just to get the feel of it. Both physically and mentally.
That said here is the slight twist that I do:
15s -- one set but go for the burn so a set could be 23 reps
10s -- two sets
5s -- two sets plus a burn set of 15 or so (if you are feeling frisky that day go ahead and do a third set --which could be just 3 reps)
Negs -- same as 5s.
There has been alot written about "clustering" it is simply focusing on your reps and not your sets. So the number of sets is the variable in the equasion --- the number of reps is not.