does it work withe the panniers and the tail tidy?

I can't see any justification for Triumph saying that this will void the engine warranty. The engine and gearbox is designed to work across a wide range of road speed and engine rev combinations, and the flat torque curve facilitates this. All this may do is slightly shift the typical gear change points, and I'm sure that has much less effect than the variation between riders in which gear they would select for similar riding situations. In other words that seems like nonsense!

If anything this mod gives the engine an easier time in high gears and at high speed, without any noticeable adverse affect on top gear roll on acceleration, while at the bottom end the change is not enough to cause the engine to struggle in the lower gears. On a recent trip I still found it fine to go around small traffic islands in second gear without lugging the engine, and always had the option to change down to 1st if required, and there is absolutely no situation where 1st gear is now to highly geared, as it was far too low originally.