I have not, but you can set up a free FogBUGZ database and see this for yourself at
http://www.fogcreek.com.
Note that the expansions are typically a number of lines long, with carriage returns in them.
I haven't had any problems with Safari, Camino or FireFox, or with Omni until you re-integrated the "+" multiline edit feature. (Since expansion is done within the DOM, they're inactive when "+" is used.)