I should have also asked: when you made your profile using Argyll, what parameters did you go with? I've found the XYZ cLUT options to produce the smallest Delta Es, but I'm not sure if it's just overfitting the target patches and might not be the best for general purpose work.
xt2ti3 -i -v infile scanner1
colprof -v [-bn] -ua -qh -D scanner9800.icm -O scanner9800.icm scanner1
colprof -v [-bn] -ax -ua -qh -D scanner9800m.icm -O scanner9800m.icm scanner1I usually leave out the -bn option as the reverse table, b2a0, isn't used.
XYZ Luts are slightly better. Probably because the scanner, like a camera, uses RGB filters and XYZ is a somewhat better match.
I've been using a 957 patch file for scanner profiling and it does a pretty good job creating scanner profiles but I'm in the process of making a 1914 patch tables because the errors that remain are mostly in the darker, and saturated blues and cyans. And, for various reasons, I prefer using the LAB PCS luts rather than the XYZ PCS. These profiles work far better on prints than using the IT8 target profile which isn't very good for scanning inkjet prints. It also suffers from having a really low L* max. It's about 92 on the IT8 that came with the scanner. The IT8 target has colors that exceed my printer's gamut and vice versa so I really need separate profiles for scanning chem. process photos and inkjet prints. I'm not sure which is better for scanning other things.
I've also completed the code for scannerreflfix.exe so it works with different DIP resolutions. It also has options to embed a scanner profile and simulate Rel Col instead of Abs. Col. It simulates only boosting the L* since generally one wants to retain the tint of whatever is getting scanned. But I may add full white point Rel. Col. simulation later. Normally, when scanning something it's desired to retain the actual possible off white of the scanned image. But not always. I'll post updated code shortly.