I have not used the CSL load cell pedals, but I do use the Club sport V2, that have a load cell. I also have the T3PA pedals that I used for quite a while, as well as the 599 Alcantara rim.
So I own the TX, not the T300, so at first thought I was going to suggest the get the Alcantara, as I love that rim, and the T3PA's while not as good as a load cell, they certainly got the job done for me for a long time. Much, much better then the stock pedals.
However if you are getting the t300, the rim is apparently much better then the plasticy, toy like rim that comes with the TX. So while I haven't used the CSL pedals, specifically I would suggest get them. I love my load cell pedals since I got them. Can defiantly control breaking much better.