Since this is the first year of the new line up and you like the S-3, there should be plenty around online. Probably at good prices too. So getting one should not be a problem. For 40 series, yes there appear to be variations in the combination of cups you can use but thats only an issue for bikes with tapered HTs; you can also buy the standard complete 1 1/8 headset so you wouldn't need worry about combinations. S3 or 40 series would appear to be viable options for your Fargo.