AFAIK it's mostly a matter of personal opinion, the Thrustmaster's have the feet furhter apart than the CH pedals, there is a price difference, then there is the issue of the pots on the TM's as stated by muck.
You will not have any instant advantage, I too was on a M$ FF twisty-stick before I bought an X45 and consequently CH-peds. It takes a lot of getting used to. I'm not a RL pilot so this was a totaly new experience for me, and was uncomfortable at first.
Now that I am used to the pedals, I much more prefer them over both the twisty method and the rocker method (found on Saitek). I can say that for me, I have greater & finer control of rudder input with the pedals.