Hi, MnemonicGhost -
Just to clarify, is the music on your phone and thumb drive downloaded from the same source?
They are regular MP3s (LAME VBR if that matters) with a fairly well organized folder structure. (Artist / Album / Track# - Trackname.mp3). No DRM at all. 70% self burned, 30% from amazon. I have 2,300 songs on the thumb drive, so I'd guess I had around 3,000 on my phone.
There may be a random GIF or JPEG in there for album art, and sometimes a PDF for the "digital booklet". But essentially the same content on both thumb drive and phone. Just alot more content on the phone due to available space.
The USB drive option is definitely the way to go for the moment. I didn't think you could actually index music on a phone via USB though. This is news to me?? I have a HTC EVO 3D so I'm in the same ballpark. How did you mount it? As a disk drive??
My last phone (Motorola Atrix) was a pain. I sometimes had to switch the Sync system to USB twice for it to fully connect. I do blame the phone for that as I had tell the phone how to treat the current USB connection. I would choose "USB Mass storage" and it would never remember it the next time. But it's 16 GB SD card was chock full and it would get loaded in the sync music library after about 4-5 minutes.
The HTC is much better. My One X+ doesn't ask me anything, but it still tries to go into USB Debugging mode no matter what I connect it too. Seems to be a developer function. Will play that and other settigns to see if I can get it indexed faster. Otherwise the USB thumb drive is working great.