I went with the Lindop chip specifically because it keeps within the Toyota parameters rather than risking an aftermarket offering. The only time I felt a really needed more power was with towing and to that end I'm very pleased with the difference, no more dropping into 4th and back up to 5th with the caravan on motorway inclines.
That said, it's nice to have the quicker pickup during normal running. It does kick out a puff of black smoke when you hit the accelerator after each gear change but assume that's the extra fuelling in the system when you've dipped the clutch so I'm not worried about it.