I guess, it will be pointless to buy US rns-e units now
 

<center><img src="http://www.navplus.us/forum/album_mod/upload/fb69e808c1ddeb262179e1d51c61da3c.jpg"></center><p>
there is a post on navplus.us about firmware replacement. Check this out<ul><li><a href="http://www.navplus.us/forum/viewtopic.php?t=2723">More info here....</a></li></ul>

There are still minor differences
 

If you open the RNS-E you can see that the radio tuner is different dependent on the region the unit was build for. Not that it makes a functional difference right now but there is at least a technical difference.

what about ones with SDS?

This function work only for phone (at least for now)
 

But for that youdon't need special navi unit. There is a link on navplus.us about this<ul><li><a href="http://www.navplus.us/forum/viewtopic.php?t=2895">SDS phone functions demo</a></li></ul>