I don't know how you are planning to do this but to be able to specify a tag would be good... Maybe boolean would add or not add title tag, or a string would become the tag.
echo $this->headTitle(true);
// <title>My Title</title>
echo $this->headTitle(false);
// My Title
echo $this->headTitle('h2');
// <h2>My Title</h2>
And / Or implement another placeholder helper for titles, which is then extended by headTitle and in turn can be extended by our own classes. I use a pageTitle helper which is basically a duplicate of headTitle, if this could be based on a concrete implementation of a Title Helper it would make it all work more seamlessly.
Scheduling for next mini release