This may or may not be reasonable, depending on just how the Edge is written to handle locations, but it would be nice to be able to define whether /sdcard points to the internal storage or external storage.
Something like mounting the internal in /intsdcard and external and /extsdcard and then an option to specify which one /sdcard points to.
This would allow us to store application data, etc. on an external SD card if desired, since most apps do not have an option for where to store their data and always go to /sdcard. There are some apps some would like to use (such as WikiDroyd), but cannot take full advantage of (like using an actual Wikipedia dump) due to them storing their data in /sdcard, which does not have enough space for large datasets.
(If the internal memory and sd card were both using ext2/ext3, you could theoretically - if there was an app that would support making them - just go in and symlink the data directories for certain apps to your sdcard to put their data there - actually this would work if the internal sd memory was ext3 since that's where the symlinks would be - symlinks can be on an ext partition and point to a location on fat, but alas they are aren't using ext.)
As I said, this may not be reasonable as it may require a fairly hefty overhaul of the Edge setup to ensure certain things (like applications...) are always installed to the internal memory, but it would be nice.