Ok, now I'm certain.
The Saxons are more than just easy a whol lot of the time.

First, I used them for a 10 year testrun to check for the siege-bug. I never did anything and nobody did anything to me either. I had actually chosen them for this very thing to happen (aw those Saxons are not worth it, they are poor and out of the way, lets go plunder Constantinople).
Then I hear a friend say that he had never played an easier game in RTW, he simply rolled over the WRE.
Now this and several others.

I think it is partly because the Saxons are like the English of MTW, secure and out of the way. And then there is the fact that the hordes do not go north, rather southwest, well away from Saexland. That means that the Saxons have the enemies working overtime to deal with that while they are free to do what they want.

So you want a challenge? Don't pick the Saxons.
Though I'm happy to hear RabbidGibbon has experienced something better, so it can be challenging, though I think it is stacked against that.