I'll echo the 1J bolty vibe. I love shooting a no MED 'sniper.'
As for general play, it does depend on the site. At Gunman Tuddenham I'll use the 1J bolty, as it is a small site. For a larger site, I'll use the M14 DMR as I have space to pull back. I NEVER take position without knowing where I'll go to next though. I have never used my sidearm in years of playing. Usually it gets left in the kit bag. Playing DMR well takes a more measured playing style.
TBH I usually play support gunner with about two milsims per year with a DMR (on large sites), so listen to Impulse and Concretesnail rather than me for experience. I do what I do though, and an accurate 1J is a fun option. A semi locked CYMA M14 works for me too. It's worth a go I'd say.
Remember that repeatable accuracy is king though. All the power in the world is no good if it's in the wrong place.