The TMS that comes with XF. The add-on that contains the template modifications will also add extra functionality for my live site, so when I am finished with it I just need to export the add-on from my dev site and import it to my live site, and the new new style changes will be applied along with the extra functionality. Zero template edits, yay,
Some of the things I use the TMS for in my new style is to increase the postbit avatar to 148px by 148px regardless if the members avatar is rectangular or not, move the Nav Tabs to the top of the page and fix it in place along with the moderator bar & login bar, and set the Top link in the footer to take the visitor to the correct spot at the top of the page (taking into consideration if the visitor has a moderator bar, or login bar, or neither), move the breadcrumbs around, and a few other things.
In my opinion using the TMS for these types of things is really convenient, and maintenance free. The best part is, you can apply the changes to one style only or all styles.