Does Bluetooth Latency come from the Transmitter or Reciever?
To begin, aptX is an algorithm that is used to compress-decompress sounds on the fly; this is often called codecs [short for coder-decoder]. It is similar mp3, mp4, and wav algorithms but these are intended to be embedded in the hardware itself. Therefore, one can conclude that there could be less delay in some codecs, but it is not really detectable by humans. However, the quality of the sound might be more noticeable than the delay.
At the end, aptX or no aptX you are still using Bluetooth. And yes, aptX might improve your audio a few percentage points but the aptX might just be marketing propaganda.