In reply to hcmcsec:
I've done that tour about 10 times - as it is one of the nicest and most varied tours in the area - usually from the bottom to the top in a day. I'd say doing it in 6hrs is normal, though I've heard of 'guidebook' times of up to 12hrs, but have managed to do it in 3:30 myself, without running.
I know that many people now bivy by the construction site - there is a large, flat plateau region. If you do do it in a day, I'd recommend leaving the parking lot in Hammersbach before first light. The 'toll' to the Höllentalklamm tends to open around 6:30-7, which will force you to pay a unnecessary fee (also, if you leave as early as possible, you'll only get a mild heat stroke when crossing the scree slopes before the glacier
You might also want to check with local guides about the condition of the glacier - most people don't rope and only a few use crampons, if the conditions allow it. A good company to call/email about this would be vivalpin.de
As to the route itself, it is, as I said, one of the best and most varied tours in the area. Starts through a wonderful gorge, then up along a nice plateau, then a small via ferrata, then a rather gruesome scree section, then a glacier and final a longer via ferrata. And be sure to prepare yourself for the culture shock when topping out into crowds of tourists staring at you as if you were an alien.