Big differences between the two cases
1) Brawn was very open in 2007/8 in regards to how the rules allowed for a double defuser and very few listened (and remember other teams actually had them too, its just Brawn where the most successful)
2) They were always complying with the current rules, I dont believe they were ever at risk of being banned, just not able to use the DD going forward (once the FIA Council sat and decided)
3) RBR were warned several times during Australia that they were contravening rules and ignored the FIA . Yes they did break the rules otherwise they would not have been excluded from the results as they have been
1) Redbull have been very open about the fact that they didnt breach the rules, and that they can prove this. The technical directive they did not agree to was the offset the FIA advised them to stick to, which they didnt have to because it was a directive not a rule.
2) Again redbull are complying with the rules, this time however the fia has banned now rather than leaving the hammer looming. Brawn were always running the potential of being DQ'ed from the opening rounds, it was spoken about at length.
3) RBR were warned that they were in breach based on the directive set offset that RBR did not agree with and believe they have sufficent evidience to prove that they have not breached any rule. Being excluded or not is not proof that they have breached the rule, it is merely further evidence that the FIA doesnt have a fixed president for how to deal with certain events.
4) there is one FIA Homologated device yes, the teams will all have different ways to measure fuel flow. Redbull have advised that they monitored the fuel flow via the injectors, pretty sure others will monitor in there own way as well.
My point is about the fact that Redbull have not breached any rule. They breached a technical directive, the two are different.
Even if Redbull have sufficent clear evidence to prove they were not in the wrong the FIA needs to be very clear with this ruling. If they overturn the DQ they need to make it clear how they handle such situations in the future. My hope is that the FIA stick to their guns and maintain the decision for the ban, otherwise its going to open up a whole can of worms about how teams measure fuel flow, my fear is that Redbull will be able to prove beyond reasonable doubt that the FIA sensor was fubar and they were comfortably within limits at all times, and the FIA have no choice but to role over.