Hi Renee,
Welcome.
I don't know the 55, but I have made the switch from the 24/Tatum to the 14/20/Speakman and there are a lot of new techniques for me to learn.
As far as I'm concerned, the more you can learn, the better, so after you get the 55 down, you can always learn the other techniques in the system.
Then decide for yourself.
--Amy