DrDoc - 7:12 pm on Jul 3, 2013 (gmt 0)
Personally, I would use
<br> and have not noticed any drawbacks. The length (i.e. number of words or letters) of the header will likely have a greater impact. Also, misuse of
> can have a negative impact (i.e. markup of content that isn't semantically a header).
As an aside -- I notice that you appear to be using XHTML markup. This is considered harmful unless always accompanied with the appropriate
application/xhtml+xml Content-Type. You are much better off forgetting XHTML ever existed (unless you truly need XML capabilities in your document) and stick to HTML4.01 or, better yet, HTML5.