my hartke experiences are three.
first, in the 90s i did blow out a hartke aluminum speaker (it ripped like tissue paper), but while my wattage was well within its specs, i play with a lot of attack and hadn't yet learned that made a difference. after that i blew out a peavey black widow LOL
second, my beloved hartke LH500. it is still my favorite amp that i owned - what tone! - but alas, shoulder damage means it was hard to move, and i prefer a smaller amp.
third, my husband has a little hartke HD15. it has more low end at lower volumes than any similarly sized amp i've tried. it's definitely got the beef.