Apr 20, 2012 - 6:29 PM
Yes, long day indeed but possible. Muveran provides very good info. As you can see, the transport out of Griesalp (via bus) is infrequent, only once every two hours.
I'm sure you know that Höhturli is one of the most aggressive passes to hike over (at least of those that don't require mountaineering equipment). However, starting at Oeschinen rather than Kandersteg cuts about 1300 feet of vertical ascent out of the hike. So, given your background, I'd say you can definitely make it in 6 hours.
Perhaps stating the obvious, but don't go if the weather is bad or forecasted to be so. Höhturli gets whited out pretty easily.