I almost bought the Agent Rocker 1-2 years ago after trying one, so here is my 2 cents:
From what you are describing it makes no sense to get another board unless it is a dedicated park or pow/freeride board. The Rome is super versatile and should cover your all-mountain and general park needs easily, probably better than a Machete or Proto (I also looked at those).
And why do you think the 159 is too long? At your weight it sounds about perfect - I weight 25-30lbs less and would have gone with the 157 for myself. 159 also has more edge hold for the icy stuff.
I'm not sure if it's too long as I haven't ridden it, it just ~feels~ a little long and stiff hopping around on it in my living room. Maybe that's because I'm coming from a 156 burton V rocker Custom (not flying V).
I want to pick up another stick so I don't get bored with the Rome to to probably riding 15+ days this season(and maybe I will absolutely love it and not get sick of it). Just makes me nervous going out west with a board i've never ridden.