Do you know how to use soft proofing? I ask because before you condemn the profiles you are using I need to know that you are using those profiles correctly.
Making your own profiles may or may not meet your expectations...in the case of Epson supplied profiles, trying to make your own profiles and expecting better results is not really reasonable. Epson profiles are very, very good and I expect that you are not using them to their greatest potential. I can't speak to the Illford profiles since I don't use them.
Just understand that making BETTER
profiles than what you already have isn't the holy grail...you may actually be better off having somebody (like Andrew, the Digital Dog
) make your 3d party paper profiles for you. Just getting the software and hardware will not make you an expert. It takes a degree of expertise to use color management tools. I mean no disrespect, I'm just trying to explain why you might not be a good candidate as a custom profile maker...just sayin'
I tried to make profiles that were better than the canned profiles supplied by Epson. 6-8 years ago (the 9600/7600 printers), I could...in the last couple of years (with the recent printers and Epson profiles), I simply don't waste my time. I know the (many) of guys making many of the profiles for Epson and I know they know as much or more than I do about making profiles...
If you are using exotic 3rd party papers whose makers don't supply great profiles, then yes, you might be able to exceed the generic canned profiles.
You really need to understand what will be required to accomplish what you think you want...just doing it yourself is NOT always the answer.