Transposing can be a little awkward if you don't get pedantic about tunings...
If you're playing one shots or loops (synth style) on the ESX's keyboard part make sure you know what scale you're using & then transpose both parts simultaneously. This means chord changes will always stay in tune (if you're not playing tonal notes on the drum parts). If you only want to transpose one part of the sequence at a time try transposing to notes from the same scale you're playing. This will mean everything sounds locked in. You'll almost always do right by using 5ths or the correct 3rd (natural for major, flattened for minor).
Hope that helps, couldn't tell by your question if you know much music theory or not...