Hardball or softball

Following my resignation, the offers keep coming:

• A more senior position in the company.
• A salary raise commensurate with that position.
• Charge of the graduate recruitment programme in consulting and research.

I've spoken to the Employment Tribunal Service however and they tell me that in only 1% of cases does the board believe that a grievance is sufficiently malicious for them to award employer costs against the employee. I also have an idea of costs for a legal representation through an employment tribunal.
The question I have to ask myself is, what would be able to let me stay? Is there a way I could draw a line in the sand and continue in employment here? Or do I want to burn all my bridges when I'm going to be looking for other work in future?
The easiest -- but least satisfactory -- course of action is just to walk away. I'm not prepared to do that:

• I don't want it said that I left because I just couldn't hack it, that I got a poor review and got arsey over it.
• I need to establish that they discriminated against me because of my cancer.
• Could I be really onboard for the graduate programme if I have doubts about the company?

So, there's nothing that'll make me stay, because I've lost faith.

Updated:
Now I've articulated my position to the head of HR, things have turned a little more hardball. They're completing the grievance process at a subsequent meeting and will take the view that they've made every attempt to resolve the issue. I will say that they did this only once I'd resigned. They'll say that the process wasn't complete and that I could have appealed before I resigned, but chose not do do so. They told me the process was complete, but I have no witnesses to that, so it'll be difficult to prove. I'll tell them that I'm going to an Employment Tribunal. They'll say fine and won't do anything until they hear from the service, which means I'll need to pay hundreds of pounds for a lawyer when I shouldn't need to. If the tribunal sits, they will lose, but I won't win much because they'll claim I didn't follow the whole process. It's a stupid way of doing things, but they forced me down the hardball route.