This is a tough one Josh.  I understand your dilemma.  My advice would be to not go any narrower than your current board OR to go with a mid-wide instead of a full wide.

Well can we agree that what matters the most is the width of the board where your foot is positioned over it.  That is where the force (weight + leverage = power) is transferred from the rider to the snowboard.  But with all of the measurements and specifications that board manufacturers offer us, none of them include this specific width position measurement.  Well, let's just figure it ourselves.

First let's assign a name to this new measurement.  I will just call it Mid-Width for now, but I would rather call it something else since that could be confused with the term "mid-wide" which we already know s a classification of overall snowboard build width not a specific point of measurement -- but whatever, we can figure out that name thing later.

On your current board with an effective edge of 118cm, your stance width of 22 inches (or 55.9cm) is almost half of that.  Your stance width is measured "center-to-center", so effectively your bindings are contacting a few cm's past that to make it more or less half the running length.  This makes our estimation easy.  Lets just take the Waist Width and the Tip Width (usually the same as the Tail Width especially on a freestyle board) add them together and divide by two -- essentially an average of the narrowest and widest widths of the board. 

(note: This measurement is not EXACT for the width of the part midway between the waist and tip/tail.  Figuring that would take an equation that is crazy complicated and since we are not landing a lunar rover, the average way is good enough for what we are doing)

BOARD	Tip/Tail Width	Waist Width	Average (Mid-Width)
WWW Wide 153 Rocker	30.38	26.1	28.24
WWW Rocker 152	29.23	24.9	27.065
Current Board	29.46	25.2	27.33

As you can see, the mid-width area of your candidate WWW Rocker 152 board is nearly the same (only .7cm narrower) as your current board, so you are not likely to notice any considerable difference.  However, with the candidate WWW Wide 153 Rocker board, The mid-width is 28.24 (or nearly 1 cm greater) than your current board.  You are more likely to notice a difference with the wide board.