My good experience w/DriveKey on PC and MAC
I've picked up a used American NTSC Wii (with latest firmware) and Drivekey at Consolesourse.com about 2 months ago. I've had really good luck and so I thought I would share with you what I've been doing. So far I've made over 50 backups and they all work 100%. The only game I've had a problem getting to work is Ghostbusters. I think it might be the dump. Everything else I've burned at 4x speed (using Disk utility on the Mac OSX or Imgburn with Windows XP/Vista). I use Verbatim white inkjet printable DVD-R's (16X, 4.7) I get these in 100 packs at a local outlet store cheap and I like the look of the white discs. I've also burned 5 Gamecube games (Leg of Zelda, Baldurs Gate, mario Sunshine, Sonic Adv 2, and Burnout 2) I also burned them at 4X with Imgburn and Disk Utility with no problems.
As far as dual layer, for Metroid Trilogy I downloaded the version that comes with 1 and 2, and downloaded 3 separately. There is also a special version of SSB that is single layer, minus some movies and what not. I havent tried that one yet, so I can't speak for it's completeness, but the Metroid trilogy works great! I've never had luck with dual layer discs they are expensive anyway, so I think this is better (especially since there are only those 2 games for Wii that use DL, so far)... The only other thing I've noticed is some stuttering audio in the video cut scenes in Super MArio Galaxy and Warioland Shake it! Fortunately it's only the intro videos that do this and it's just slightly annoying.
it's just that simple. Imgburn with Windows is free and straightforward and it will even burn Gamecube images in the proprietary .gcm format. Using Diskutility in OS is just a matter of right clicking the .iso file and then highlighting it and pressing the burn button. 4x speed works everytime.
All the .iso's I've burned so far for the Wii and cube have been NTSC USA versions many of them were scrubbed beforehand but it hasnt made a bit of difference.
Sounds like you're getting along famously. Ghost Busters is a notoriously difficult game to run. There are shed loads of posts and guides about how to get it working.
Best of luck.
I'm the same here, no problems except for some stutter, but I was expecting that! SSBB single layer doesn't work for me, but see how you go and keep us posted!