Did you know that you can easily load Greasemonkey scripts into Opera? While Firefox users need an extension for that Opera users can simply import them into Opera. Well, some manual work is required but nothing to serious. Takes probably half a minute to import it.
First you need to download the Greasemonkey script that you would like to use in Opera. You may need to rename that script so that the file ends with user.js if that is not already the case.
Opera needs to be restarted so that the scripts can be loaded once the folder has been selected. After that it's just a matter of testing the scripts on whatever website they are working on.