For me there is no cost, but I rarely do the cycle-through-all-tabs thing (not never but rarely). For your workflow it sounds like there is a cost. If you work on multiple projects in the same editor instance then there is a significant cost as well, e.g. you may have 5 index.html files open and when you type the desired filename you then have to choose carefully. I have encountered this when leaving Emacs open for days or weeks at a time, switching between personal and work projects.
These days I use TextMate more than Emacs and for small personal projects I like quickly switching between say the readme, makefile, code, and test with Cmd-[1-9]. If there are few files to edit tabs can be advantageous. This stuff is highly personal and dependent on workflow.
I remember with positions of tabs, rather than the names of files. To each their own, but there is still a need for some sort of tab behaviour for some of us.
These days I use TextMate more than Emacs and for small personal projects I like quickly switching between say the readme, makefile, code, and test with Cmd-[1-9]. If there are few files to edit tabs can be advantageous. This stuff is highly personal and dependent on workflow.