Well with an ex-subs Sky HD box you'll get around 200 FTA channels, full channel listing
HERE, Plus BBC HD,ITV HD(with the new EPG) and Luxe HD.
Also so long as you keep your old viewing card in the Sky box you'll also have access to 4HD,Sky3,Five USA,Five USA+1,Fiver or Fiver+1,as they are all encrypted but free to view(FTV) channels.
But you wont be able to use the record/live pause facilties without a Sky subcription!!!!
With Freesat there's only 140 channels on the EPG itself,channel listing
Here,
Though you can access the other 60 or so extra channels that Sky has by using the Humax HDR in "non-freesat" mode,and you will have the benefit of being able to record all those channels.
You wont have access to 4HD,Sky3,Five USA,Five USA+1,Fiver or Fiver+1 though,because as mentioned above,they are encrypted channels.
There's no dish repositioning needed, Sky and Freesat receive the same broadcasts from the same satellite(s) so it's just a case of swapping cables and the Humax is a piece of cake to set up.