X10 Dynamic Range (EXR vs 12MP)

Hi everyone,

Cross posting from another forum in hopes of reaching a wider audience.

I have been really enjoying my new (to me) X10.  I have read a lot and I think I have a fair understanding of the various modes (EXR Auto, EXR with PASM at M or S size, etc.).  I will be doing my own testing as I shoot more with the camera but was hoping to get some input from others that have owned it for longer.

As I look at DPReview's dynamic range charts for the X10, it seems that the EXR DR400 and the the 12Mp DR400 have identical dynamic range.  Other than the fact that the 12Mp DR400 would require you to use higher ISO, are there any disadvantages to using 12Mp DR400?  I like the images I get with the EXR DR400 mode but I am always a little uncomfortable with "ditching" half of the camera's resolution.

Thank you!