I have done a very similar day hike in the opposite direction although I started on the Easton side of the mountain rather than Franconia Notch. The ascent up the North Kinsman is quite similar from either side of the ridge although Cascade Brook trail is bit longer. Unlike many folks I prefer going down steep stuff and wanted to get the hard mileage done early. It took me around 10 hours with daypack. I had stashed a bike in Kinsman Notch and slowly biked back to my car at the Mt Kinsman trailhead. As noted there are lots of PUDS after descending South Kinsman. A note about the south face of South Kinsman. Its relentlessly steep with about a half mile of near vertical boulder climbing. The AT down the north face of Moosilaukee (Beaver Brook Trail) is steeper but most Nobos are descending it so the climb up South Kinsman is a NOBOs first real introduction to white mountains trails. The climb up Glencliff trail on the south side of Mooosilaukee has far more vertical gain but compared to the south face of South Kinsman its far easier.