I have just ridden Oblivion. Its a good thrillride with a perfect dramatization of the drop. Sadly the fun ends after that, cause the machine doesnt offer more than this.
The G5 has no tunnel, the entrancé is located halfway up a mountain, so the design is absolutely the same (its a mirror image though).
I have not seen decent pictures of G5 showing the full drop, cause i would really like to see the complete drop.
Oh, i bet you know all this, i forgot i was posting to god ;)