In the GlobalUserContribs tool, I suggest changing the default sorting method to the newer "by date" option.
Additionally, moving the message string "Limited to 20 results per wiki." from the bottom of the page to the top, would be helpful for both modes.
Because: Most times I use GUC, I'm clicking through to it from a link on a wiki with a username already selected, and therefor I have to wait n seconds for the "by wiki" results to finish displaying before I can re-run the request with "by date" selected. "By date" is almost always the result I need.