Well, only you can tell whether it's too hard for you. The information on veloland.ch, including the height profiles, should give you an idea. As long as you're used to hilly routes on a bicycle, however, you ought not to have any problems.
I did route Nr. 9 last year with my father (age 64 but rather fit) and I can say that it's very nice route with some moderate climbs. There is a page about it on our Wiki (
Seen-Route), text in German but you will find pictures, a track and more profiles.
I have not done Nr. 4 (though I'd love to do it one day), I reckon that it is more difficult than the other one.
Stefan