CHG_CANON wrote:
How high of an ISO do you want to use? At that ISO level, how does your current camera look? Is using a flash a better approach than a new camera?
If the candidate cameras have been out for a while, there will be detailed reviews and example images from ISO-100 through their highest ISO. Compare those examples against each other and against your current camera's results. Look at the 1:1 pixel level details.
Make an informed decision using these freely available resources.