The DP200 was my first dashcam 18 months ago - daytime colours were muted but the night time quality was very good to be honest, especially seeing as it was coming out of an AR0330.
The issue I had was that I had too many vibrations through the mount so I sent it back and bought a GS6000 A7, but then that had all the issues of the early Ambarella A7 cameras so I then sent that back and bought two GT680Ws which were very good cameras for me, just without parking mode at the time with the versions I had.
If I'd have known back then it was a standard DOD style mount on the DP200 and I could use a multitude of other mounts I'd have probably stuck with it, but as things turned out many cameras and many hours later I ended up with better solutions in my car (I'm currently running the SG9665GC like yourself, the Panorama X2 and the Lukas 9370)
The vibrations were all mount issues in my car and it just didn't work well for me - the shorter mounts would have been better and they can be picked up as an option now.
In terms of picture quality the SG beats it - it just doesn't do the Wifi yet and the Transcend has the more obvious hanging form factor as opposed to the SG which you can hardly see when placed behind the black dots at the top of the windscreen that most cards have.
There is the Wifi version of the wedge coming though as you can see it on the advertising in the booth at the last two SG shows
I only ever tend to use wifi on cams to set them up though and then don't really use it after that