I'm new to the game but I've played a bit of Rogue trader. My group is choosing characters and I'm planning on playing a Dark Angel devestator marine. My ony other exposure to the setting was playing some Necromunda in the mid 1990's. When I played Necromunda I was always enamoured with that sexy plasma cannon that I could never afford to get for my heavy. Now I'm thinking that I'd like to work towards getting access to one for my devestator, bu *** looks to me like my standard issue heavy bolter is gong to do as well most of the time and I can get several talents to make the bolter better, and because it is cheaper It would be easier to get access to better scopes and fancy ammo.
For me, unless I'm using a really flexible system (such as Ars Magica 5 with lots of supplements or Hero System), playing a character that's significantly sub-optimal is like having a moquito buzzing in my ear. It's a sort of low level annoyance throughout the entire game.
So my question is are there ways to make plasma cannons sufficiently competitive with Heavy Bolters so that I can revel in their blast radius coolness while avoiding the feeling that I'm playing a character who's become artificially weak to accomodate the style choices that I've made?