A full run takes about 46 min on my 32-bit Windows setup. Most of that is iridge. If I take out just the parts for S09, it's about 80 sec. So I did that, and started tinkering with the number of retained PCs. Ultimately, I want to see how much of the difference between RO10 and S09 is due to this factor.
For the moment, I have just plotted the all spliced trend maps for the period 1957-2006 for retained PCs from 3 to 7, using the RO10 implementation of Steig's method. Here they are:
3 PCs retained
4 PCs retained
5 PCs retained
6 PCs retained
7 PCs retained
8 PCs retained
9 PCs retained
10 PCs retained
As soon at Steig's method retains more than 3 PCs the trend plot comes to rather more resemble Ryan's, at least for 4:6 PCs retained. With 7 there is a change, which suggests that perhaps noise is becoming a factor.
Update. Here are the average trends for the various regions, in C/Decade. They are comparable to the values in Ryan's figure. Note that with higher PC numbers, there is some movement towards Ryan's values, although a significant difference remains. There is also a big change at 7 PC's, suggesting that this is the noise limit.
Update 2. I have added the cases 8:10 PCs retained. It seems to confirn that things get ragged once more than 6 Pcs are retained - possibly noise, though Ryan hints in comments that something else is involved.