Stock Nav or Aftermarket

[donmayor]

I recently acquired a 2003 X5 with Sports Package. The previous owner replaced the stock NAV with an aftermarket pioneer one, picture below:

The pioneer NAV currently on there, has DVD, Radio, XMradio, but the screen is small, 6.7 inches:



I want your opinions on whether i should stick with the current NAV system or switch back to stock or get a better aftermarket with bigger screen? And whatever you suggest, if you could also suggest the specific NAV system to get.

Thanks in advance,
DoN