But the faction system makes it easier for the Saxons to get back into power after losing the invasion. Played through two games now post 1.07 and had Saxons back on the throne very quickly.
I'm playing a Shrewsbury to Duchy of Hereford Saxon game right now. I managed to keep all my counties during the invasion and helped put the grandson of Harold Godwinson on the throne. Good fun.
As interesting as that is (and I enjoy those sorts of games, and especially now Ælfwine Haroldson is a legit bastard) it's also the reverse of what ought to be the case. In terms of starting internal factions to install 'one of their own' in a post-Conquest England, the Saxons had next to no chance. When they did attempt to rise up, the Normans beat them decisively, imprisoned them and stripped them of their lands. You can do this in game, and historically this happened when William was busy fighting the French and Bretons in Maine, which makes it all the more interesting and impressive because the Normans won under a new and fragile regency.
In terms of the actual Stamford Bridge starting numbers, though, the Saxons should have a clear advantage. They decisively beat Hardråde and Tostig's force, killing both men in battle, and then force-marched across most of England and fought William's force, which they almost defeated, despite being in a pretty battered way and at low stamina and morale. The Saxon shield wall on Senlac Hill pushed back the Norman heavy cavalry several times, by which point William was seriously considering withdrawal. It was only because the Saxons then thought William was dead (I forget the details of this, but it was either just bad luck or a piece of good propaganda on William's part) that they broke ranks and charged down from their shield wall, at which point their defensive advantage was lost and the Normans regrouped and won the day. The numbers would have been very close and had they stayed on the hill they'd probably have won.
None of this is possible in CK II of course, because Paradox have decided that it should not be possible for the Saxons to win under any non-exploitative conditions, despite the fact that the Normans could (and often did) win in 1.06, in which the numbers were much more realistic,
and there's even a second 1066 scenario for people who want to start after a successful Conquest.
I find it frustrating and annoying that, despite adding and fixing Saxon characters, they continue to make it impossible for them to actually survive. Doing what Harold Godwinson did historically -- namely, handing Hardråde his ass on a platter and then fighting William with good odds of victory -- is an impossibility in 1.07 and 1.08, and for that reason I can no longer play my favorite scenario.