Yep, lots here think the E2 & E3 are overdone. "Busy" is a good description. But then again, I wasn't that fussed on the G8 front, especially the fake hood vents, but it's all personal tastes anyway.
You get (or got) the LS3 in the GXP, so you only missed out on brakes and suspension (being the major differences) to an HSV.
With the new Chevrolet SS, I think you'll still get two engine levels once again, but probably not any HSV variants or "parts" (apart from the LS3 which is a GM component in any case).
Don't forget, Walkinshaw owns a majority share of HSV, with the remainder Holden owned, so any HSV bits are not straight profit to Holden / GM - they have to share it with Walkinshaw