The Wiha Torx Plus (T5+) I bought from Micro-Tools Europe (IP5x40) worked perfectly and very reassuredly on all Torx screws on my N9. The Service Manual I have says the chassis screws are T4+ but all the Torx+ screws came in and out with a T5+ screwdriver.

The Phillips screws of the loudspeaker enclosure are trickier, though, none of my screwdrivers (#0, #00, #000) would find purchase because the pointy bit of the screwdriver was too pointy, should have been flatter to engage the screw. I had to use a very small flathead for those screws.