I am an intermediate rider as well but I am much older than you (30). That being said; don't discount K2. I went from a regular camber 2004 M3 155 to a 2010 K2 Jibpan 153 with rocker camber and it is like night and day. I was progressing slowly over this season until I got that new board. My skills have increased 100% in the last 3 sessions because the board is the right size and fit for my style of riding.
Also I don't entirely agree with the no rocker because you ride groomers. I live in Michigan so all I ride is groom and the K2 rocker hasn't presented me with any issues at all.