>For our new design, we decided to stick to a fixed grid of 980px.
Yep, this is what I've been doing for a while now. Looks great on desktops, and looks great on iPad devices and tablets.
Responsive sounds good on paper, but when your 1 person in a team of 2 startup, you can't afford to waste time like that building something truly flexible. Not worth the time investment.
Again: MEASURE your audience. If your mobile visitors are a small percentage, it ain't worth it. Let them pinch and zoom.