Have ridden a couple Nitro boards and its a whole different game to some of the park flex/jibby boards. Nitros are one of the stiffest boards i have ridden, you may want to consider going for something with a all MTN/park flex (Something like a Ride DH/2, Rome Agent, Burton Hero) rather than a dedicated jib/street board just because it will be more fun for general all mtn riding and you may find that it fazes out your Nitro. (if you go this route, 152-154 is a better size to go for)
Also what size/weight are you cause this is a huge part of choosing a new board.
If you are sure you want a dedicated jib boards a couple that I've ridden that come highly reccomended are Lib Tech skate banana. Rome artifact. GNU park pickle. Burton Dom, K2 WWW, Ride Machete. These all ride really well in the park and the street. If you go this route, 150 should be short enough.
I would also urge you to try out a reverse camber board (Lib tech, GNU, Rome listed above and Burton Joystick) are some of the best RC boards I've ridden and are really fun to ride, not sure how cheap you would get them though, seeing as its relatively new.
Best thing to do is pick a couple boards you like the sound of and try to find a demo version this usually costs ($40NZD) and can save you a heap, possibly ride a park all mtn (eg. Ride DH2) A regular camber park board (Eg. Rome Artifact) Then a Reverse camber (Eg Lib tech) to give you an idea of which board will suit your riding more.