tomatousb "Failed to mount. Verify the device is plugged in, and try again" and EXT4

So I've attached 2 drives to my ASUS RT-N16 router, and the first, a 320 gb western digital (WD) passport mounted without issue, where as the second 2 TB WD drive throws the error  "Failed to mount. Verify the device is plugged in, and try again" when I try to mount it manually.

My first search made me believe that this might be an issue with GPT support, but after a bit more digging, I found that the current, Nov 2011 version of tomatoUSB has already included Yaniv Hamo's patch.   Thus, I unplugged my drive and installed GParted to see what file system the drive was formatted in (yes, there are quicker ways to do this from the command line, with out the need for a software install, but I figured I'll probably want to re-partition/format anyway).  Turns out I choose to originally format using EXT4, which I was surprised by, but makes sense after I did some digging around to try and figure out which of the naive tomatoUSB supported formats I'd choose.   I hate ntfs, but EXT3 has some issues with larger drives due to a need to increase the block size.

So rather than going though a lot of data transfer and and a reformat, my preferred choice would be to reflash the router with a distro that supports ext4.  From various searches, this seems to mean that none of the open WRT variants seem to support this.  I'm currently considering debwrt, but the documentation is limited.