Best speed dongle for Bosch Performance Line?

Hi all. As the title says, what's the best speed dongle for the Bosch performance line motor? The are several available but very few user reviews etc. Apparently some are glitchy but not sure which ones. Anyone have any experience with them and can give me some info on reliability etc? Cheers

If anyone is interested I settled on the Speedchip from ebiketuning.com and it's amazing! Removes the limit but keeps practically everything else the same. The speed and distance readout etc is all perfect, no lag or half speed readouts etc. The only downside I can see is that the battery indicator immediately jumps to halfway. So far very happy