Make sure if/when you get the DSTWO you use the previous version of NDSGBA with the gamecompat.txt file or whatever it is, not the current one. Current version has lower compatibility apparently, never used it, no intentions of upgrading now that I have my Android phone, but it may or may not trigger the sound issues you were experiencing on your K1.
I'd still see about getting your K1 replaced under warranty (if they have one) since someone else posted in the thread about it working fine for them. If nothing else, your screen shouldn't look like that anyway.