Dean, it seems that you are doing this on a particualr airplane, maybe a scale one, while finding ways not to tell us what plane it is for. C'mon buddy, spill the beans. THen we'll all have a better handle on what you are talking about.

As for having too much roll control - isn't that what dual rates are for? Actually, if you are worried about a sudden Roll response, here is a general rule of thumb for spoilers:

The farther aft the spoiler is hinged, the more proportianal and moderate the response will be. THe farther forward the spoiler is, up the the max-thickness point, the more sudden and dramatic the response will be. This is because forward spoilers affect all the wing area behind them, from the instant the spoiler is raised just a bit. Aft spoilers affect less wing area and depend on added drag and changing airflow around the wing ( like a split flap) for their effect.