one problem i've had with tubular locks that are halfway in-between locked and open (typically the result of my doing the BIC pen trick without 100% success) is that sometimes one of the inner pin stacks will line up with the notch in the housing that is used to allow the key to be inserted.
on cheaper locks which don't have any shaped bottom pins, this can allow the pin lined up with the keyway notch to fall right out of the lock if you invert it. (you can just stick them back in, but if you don't have a key pin pressing against the driver it makes the lock no longer work with the original key)
so that's something to keep in mind when playing with tubular locks in the half-open position. thank god for my tubular pick or else i'd rarely get such locks closed again easily.
