From what I've seen and experienced, it's best to let things finish on their own in primary before you start messing with racking. You can rack after a week or two and let things finish in secondary, but you run the risk of stalling the ferment by doing so. Different yeasts will behave differently, and your experience will dicate how you run your fermentations.
But an extra week, or two, in primary won't generate many off-flavors from the lees contact. You're generally concerned with autolysis (dead yeast exploding themselves), which doesn't occur en masse for at least a month-ish, sometimes much longer (up to 6 months maybe). Good advice is to not rack based on the calendar. Every mead will come out a little differently, and every yeast will behave differently, so base your decisions more on SG and % of expected completion instead of "it's been 2 weeks". When you get close to your FG and activity is really slow (1-2 bubbles per minute in the airlock is a standard number), go ahead and rack to secondary. Lately I've been letting mine finish and drop lees before racking (usually between 2 and 6 weeks, depending on the yeast), since it's the lees you're moving the mead off anyway. (originally I was a calendar-racker, that caused some problems with underattenuation)
The issue with adding nutrients at racking is that they might not be needed. Too many extra nutrients in your mead can mean two things, both of which are bad: they can contribute odd flavors, and they can encourage spoilage organisms to grow by giving them food. One more reason to let things finish in the primary