While Gerstlauer are certainly possible, they have nothing in their product catalogue that really fits here.
We have:
Fast helix off standard lift hill and drop.
Switch Track
Backwards Launch
"something interesting" in the station involving moving the car into a different position in a tight space.
Gerstlauer currently do none of those things.
The Mack E-Motion coasters have turntables, lifts, standard chain lifts, car movement effects on the track, something called "flexible speed" which suggests mid course boosts or power or something, indoor and outdoor use.
However, they're essentially just family wild mouse rides, very similar to a beefed up Gerstlauer Bobsled. So I can't see how it fulfils Mr Barnes' promise of "something for the thrill seeker".
Premier do the helix off the drop, backwards launches, indoor sections and tricky track bits and backwards launches.
Both Premier and Mack rides have a throughput of around 1,100 pph - pretty close to what Alton are saying the new coaster will have. Gerstlauer are in the high hundreds on most of theirs.
It's certainly not a standard install ,and we're seeing something a little different, but I'd be shocked if it wasn't Premier or Mack as they already have the kit to do everything Alton wants in the special sections.
Details on the Mack E-Motion coaster:
http://www.mack-rides.com/lang-en/c123/default.html