I think it has to depend on the bike geometry and your physique with its centre of balance, etc. Put me down as another person who has rear panniers only and has been very comfortable at slow speeds and at speeds over 40mph (though admittedly I do use a high flat top front rack that takes my tent and a couple of other lightweight bits and pieces -point is, I don't know if I'd unequivocally state that front panniers are superior to rear panniers or vice versa). I think it's just what works for you and the bike.
Originally Posted by
cyccommute
I have to disagree. Heavily loaded front bags are far superior to heavily load rear bags, especially on something like the CrossCheck. Moving the bags to the front wheel with a lighter load on a rear rack would solve all kinds of issues with the shorter wheelbase of the Crosscheck. Handling would be better at all speeds and issues with heel strike would be nonexistent.