High levels of Paragon or Renegade ability alter the dialogue options and can shift the power balance (presumably). It is possible to have Tali found not guilty without revealing her father's work AND encourage the Admiralty board not to go to war (whether they will listen is another matter)
This is true - when I played this one, you could get Tali acquitted without showing the evidence, BUT you won't make a convincing case for peace. The evidence is a key element for that argument to be convincing. In fact, war seemed all but certain. Flotilla - Geth war is going to end in disaster for at least the flotilla and quite likely the geth as well. The special forces guy says as much - the Quarians can fight well in small engagements but their immune system is a significant liability in actual war. (He cautions Tali when she says Quarians might win such a war.). The Quarians are adept at AI, and might well employ a doomsday weapon against the Geth, as well, but without continuing the research - which they can't without the evidence, again - it will be too late to save the Quarians, I fear.
I am still concerned that either Tali OR the Flotilla can survive but not both. This is further reinforced by one of the hint lines: Your actions in ME2 can have grievous consequences for the situation in ME3, and this seems like one of them.
Worst situation: Give evidence to flotilla, they disband. Half want war & half want peace, Tali says this in engineering after you hand over evidence.
Unfortunately, that's not what she says. She says a SMALL group of ships leave the flotilla - namely, the warmongers. This means that the rest of the flotilla is not very likely to join in such a war. Which will preserve both the flotilla and the Geth for ME3.
But can we get this result without Tali dying in the collector ship?