I'd vote for getting ANY accessory at the time of purchase, that way the acc'y is covered by your new car warranty. (Tho if was reading the warranty correctly, it may say that any dealer-installed acc'y is covred for the length of the new car warranty. BUT the assumption is that a post-purchase accessory buy would not be covered under hondacare or other extended warranties.

I got the day/night mirror on my 2005 HAH which is the same mirror that the HCH uses and I like it a lot - it seems to be "height sensitive" in that it works as well on a jacked up Hummer as it would on a popeyed Geo with one hi-beam.

It's just a honking BIG mirror, with the compass thing on the bottom.

I'd lean against the XM install as it's VERY expensive and you could do after-market for about $50 and run it through the Aux plug on the radio.

OR (and/or) add on the ipod gadget the Honda Audio Link. A couple of hundred, not as much disembowelment, and keeps all your ipoddery hidden away in the glove compartment.