First of all..thanks to katjausaf, myfound and nha for working to document a working backup procedure for folks with nme mods.
Here's what I have found through the 15 coasters I've managed to burn so far.
First off..my hardware mix
360 with hitachi drive (type 47) with NME 11 wire mod installed.
The burners (all with latest firmware):
HP DVD 640C burner - booktype DVD+R DL with IMGBURN, DVD-ROM with CDCLONE
Emprex DVDRW 16x burner - booktype DVD+R DL with CDCLONE or IMGBURN
Pioneer 111D - Not good at all..booktype is forced to DVD-ROM, but I've not had any luck with this drive.
The media:
Only Verbatium 2.4x DL disk.
The games:
Personal backups of Table Tennis, Prey, Rumble Roses XX, Blazing Angels..never got to DOA4

I can get disk that fall into 3 catagories - All original disk work fine btw.
1. Disk that boot up and show the "unreadable media" error. I believe most folks also refer to this as the "dirty disc" error. The drive appears to read the disk and try to spin up to speed, after several seconds of the 360 drive clicking and trying to read the backup it stops and displays this message. I've tried adjusting the laser resistance from 4.0K ohms all the way down to 2.6k ohms and have not been able to improve.
2. Disk that boot up and display the "to play this disc please insert it into an Xbox360. I notice these disk never really spin up really fast. I've read that this error means that you have not applied the SS correctly but that it's possible your NME mod is installed correctly.
3. Disk that produce an "open tray" error. These disk never appear to do anything..I've tried the HDD soft reset on these and nothing.
I do know how to specifically make all 3 flavors. Here's a summary:
To make a disk that falls into catagory 1 you follow the wxripper procedure (no edits to the layout), use SSmerge to verify your SS.bin is valid and use NME convert.bat to build the final game.iso file. When you burn (either imgburn or cdclone) you set the booktype to DVD-ROM (not DVD-R DL).
To make disk that fall into catagory 2 you follow the wxripper procedure (no edits to the layout), use SSmerge to verify your SS.bin is valid and use NME convert.bat to build the final game.iso file. When you burn (either imgburn or cdclone) you set the booktype to DVD+R DL (not DVD-ROM).
To make disk that fall into catagory 3 you follow the wxripper procedure editing the layer (first 3 lines have their first characters changed from C to D), use SSmerge to verify your SS.bin is valid and use NME convert.bat to build the final game.iso file. When you burn (either imgburn or cdclone) and setting the booktype to either DVD+R DL or DVD-ROM.
At this point I'm not sure what to think..I've ohmed out my mod install several times and believe it to be wired up correctly but there's no way I couldn't have at least one backup that would boot. I know I've follwed the exact procedures above and have not had any luck.
Anyways I wanted to share so we can build on the info we find. I'm not sure I'm willing to screw with this anymore till there's something more concrete or a new version of SSmerge is released. At this point I'm not sure the mod is working at all, but don't know.
If I think of anything else I'll update this message..thanks!