Matt,
The geomtery needs setting up whenever the ride height is altered .

But in answer to your question, a 6° rear beam would be the my first choice before coil-overs. In fact, this is the order I did it to my car .

There is absolutely NOTHING wrong with Konis. People change them before they actually think about adjusting them (because the rears have to come off to do so) . If you feel they are too soft, just turn them up before you consider changing them . Only then should you consider changing to coil-overs, IF the Konis are at their maximum adjustment, and the car is still too soft for your driving style .