Umm... Well, we REALLU ought to be mindful about saying whether a sound system is "good" or "not nearly as great as" or etc. Iused to be (and still am) a stereo system and Home Theater collector, and people's ears aren't able to objectively tell a "good" from "a better" without some training about acoustical sound.
Until then, every time I catch myself saying "that sound system is better than.." I know I'm being almost entirely subjective, and my subjective ears are likely to be way different from yours.
Not comparing to any personal system I've had in any other brand's car:
Is the standard Non-Meridian system of the XE worth the money? Yes. If you just need the radio, and you play all you stuff on MP3s from an ipod or paired phone on your way to work, it's fine.
If you buy tickets to live performances alot, and you hear differences between a WAV file and an ACC file that you make on usb drives, and you the 11 speaker entry level Meridian is clean, precise, and tight in the XE's cabin. Meridian does not embarass itself in this car.
But the cabin of the XE is very snug ceiling-wise and backseat-wise, so making wide open STEREO magic is hard, even for the basis Meridian.
The 17 speaker Meridian pulls off the magic necessary to give you that rich stereo. I think people expect Meridian to take the extra watts and thump you all over the inside of the car. Sorry, but the English Meridian company isn't into that. The power is used to control the stereo effect and give a feeling of more open, wide stereo in such a snug cabin the XE has.
You won't be "amped up" like I'm sure a BMW or Audi tries to drown you with. The patented Meridian stereo effect is what you're extra money is putting in the car.
Hope this helps. Music really is a key part of the driving experience sooner or later...