On the list for the next call. It's really a low priority since I don't think there is much to be gained with profiles that large.
I independently found the technique for getting i1Match to handle larger charts about 2 years ago and have been developing new test charts since using my own generator software.
My current chart is 5100 patches over 3 x A3 pages.
There is a world of difference between a profile based on a 918 patch chart and one based on a much larger number of patches (2000, 4000, 5100, whatever).
However, this difference is very much dependant on the printer driver and the printer model.
In my case, I developed the new profiles to address a chronic problem I had with profiling my Epson 4000. Getting usable colour out of a printer is pretty easy, even with a 918-patch chart. The problem is getting the gray balance right at the same time.
The native Epson 4000 space (that is, what you get when you print with all management turned off) produces grays that aren't within cooee of being right with a heavy green cast.
Off-the-shelf test charts basically put test points (patches) uniformly throughout the RGB coordinate "space". In the case of the 4096-patch Atkinson chart, this is basically 16 values of red with 16 values of green with 16 values of blue.
In the case of a 918-patch chart, it is closer to 9 values of each RGB, plus some augmentation around the corners and edges. This basically puts the patches at around 28 units apart or worse.
These control points are simply incompetent at trying to control the wayward gray axis of the Epson.
I have profiled only one Canon printer - a consumer grade 8500. The test charts through that printer/driver were vastly better as far as giving basic grays before profiling. This guaranteed neutral grays, but I then have to wonder whether the printer/driver really was stepping out of the way for colour management and therefore to what degree the available gamut was being compromised.
I would be interested in knowing what you get with the iPF5000 printing a gray-scale test chart with all colour management off (as you would for a profiling test chart).
If the chart does show significant colour cast in the "native" grays, then a chart with additional patches surrounding the gray axis will produce noticable improvements.
The result I now get from the Epson 4000 as far as monochrome prints are as neutral and even as I have ever wanted.
So, run the simple test: if a gray scale test with all colour management disabled produces significant colour cast, then you really should try to use a much larger profiling chart.
The test of any profile chart is how well it produces gray tones as well as the colours.