Which size/model #/carbon content Fiberspar masts are you thinking of buying?
Check them out on this link and let us know:
The QT models (nearly all of them) are a little soft at the top, so while they will work in
your NP/Severne sails, they may not be the best choice to get the max. performance from
your rigs. You may have to do some "innovative" rigging to get around the slightly softer
As far as the 144/133 choice, how much do you weigh, and what windspeeds do you
normally sail in?
The 10 liters of volume and difference in width can make a big difference if most of your sailing is in light winds down near the minimum planing threshold, but a smaller/narrower board will be better up near the high wind limits on your 7.5 m2.
Experience is good, and the extra volume/width was a very good thing when you were learning, but maybe it's time for a smaller board, depending on your weight and the windspeeds you get.
Hope this helps,