Hi, same issue here. With small scenes photoscan perfoms awesome, and the textured model looks awesome. But for larger stuff it gets easilly messed up with the photomatching.
From my experience (hobbyst) photosynth has one of the best and fastest photomatching. Having the optionto swap the on app photomatching by importing photosynth scene would be cool.
So far, this very recently released Chrome extension exports bundle.out file of your synth
http://www.visual-experiments.com/2012/02/01/photosynth-bundle-out-export/I tried it yeterday but I believe I got an error when importing. I dont have now internet in my big pc so cant retest.
Also tried to import a bundle.out file of a simple sample scene and even if I managed to import and to see an sparse point cloud wich loked planar, after the dialog that asks me to set the accuracy etc I got nothing. This bundle.out file was build with sfmToolkit.
While I'm writing this, I'm testing the new demo 8.5 wich yes it feels much faster, but as it still take a while to compute cant say if its working in nonworking scene, but wated to share this synth to .out exporter info.