I have the 440 / 3444 as my lightweight tripod as well. It must be about five years old now and so far there is no sign of slipping locks - something to watch out for on carbon fibre tripods etc. I hang my bag from it to give it a bit of weight. After using it with the 3473 magnesium 3-D head I swapped to the 322RC2 grip action ball head which is heavier but very convenient. I'm happy to use the outfit for 35 mm and MF, but prefer not to extend the lowest leg sections or the centre column.

Best,
Helen