I've got Sibelius rewired into Magix Music Maker, and have a midi keyboard inputting into Music Maker.
If I set the configuration in Sibelius in playback to general midi, the pitches are correct, and match both live pitches and the pitch from the keyboard/music maker. However, if I select Sibelius 7 Sounds for playback in Sibelius, the notes are high by one step.
I've attempted using different instruments, different Sounds configurations, and looking through settings and configurations, but haven't found any reason why the playback when using the Sounds configuration doesn't match the notes on the score or played on my midi keyboard.