Hi there.
If you have an eye for the flickering on 50hrz sets and it bothers you then go for 100hrz. If the flickering does not bother you stay with 50hrz.
100hrz televisions come with many problems because of the proccesing the picture under goes to make it flicker free.
There are a lot of people on this forum that I think would fo back to 50hrz if they could!!
Make you sure you get a good demo of both tvs before you buy. Make sure you watch movies and sport if you can with fast movement and see what you think.
Also buy from a place like john lewis who I have heard have an outstanding customer aftercare service just in case you have any problems