First, what version of Gallery are you running? To the best of my knowledge DH has offered one-click Gallery installs for a while. If your install is aging, you're vulnerable to a lot of potential weaknesses.
Like you, I got aquainted with a lot of the stuff available from Dreamhost via one-click installs prior to converting to a more manual method. Since you installed Gallery manually DH will not be able to perform an upgrade, and will have to manually migrate all your data, plugins, templates, and other customizations after the install. Once you go to all that trouble, you might as well stay in manual mode.
If you do decide that one-click is the way to go after the initial DH install permits upgrades, you'll still lose all your customizations and templates the next time you decide to update to a newer version via one-click. Manual upgrades do not have this limitation but you should stay aware of vulnerabilities found in your extensions.
From the one-click install page:
From the wiki: http://wiki.dreamhost.com/Gallery#Updating_to_other_version