I fly all my jets with Multiplex IPD 12 channel rx (using Mpx Tx rather than Graupner) and can confirm an excellent level of reliability. If you do decide to use Mpx IPD 12 channel with the Graupner, buy the synth rather than the crystal version, and buy the PC connection cable then download Mpx's free rx software for the PC. The reason is that Multiplex 12 channel tx do data compression and their rx de-compress the data, (to improve the refresh rate) but Graupner 12 channel is not compressed, the synth IPD 12 has a specific Graupner setting to work with Graupner tx and this option is only accessed via the PC software.

Harry