These charts from comparing profiles made with 6 different patch counts using the 3 profile creation tools on each set. 4 printer/paper combinations were used. Accuracy was determined for 848, random patches distributed over the printer/paper gamut and 192, near neutral patches randomly chosen near the gray axis.
The printer/paper combinations were: Costco Glossy for the Epson 9800, Canon Pro1000, and Canon 9500 II. Matte (MP101) with the Pro1000 was also tested. All were done at the highest quality print settings. All profiles were also created using the highest quality settings.
Generally, the I1Profiler and Argyll were quite close with the Argyll give slightly better results with larger patch sets and I1Profiler doing the best at smaller sets. The differences were fairly minimal. Profile Maker 5, however is consistently inferior.
All of this data is from the 8 page, 957 patch each targets described in more detail in the crowdsourcing thread.
This is the performance across the full printer/paper gamut:
These are the results for the near neutrals: