i'm with the pan seared crowd!!
i use a quality olive oil and keep it hot but not smoking.
i add my spice of choice(cajun" usually) right to the oil, so the heat releases the oils in the dry spice.
then i sear both sides and that's enough to cook the fillet unless it's extra thick.
for trout, it's best IMO grilled over the fire so the fat can drip off and yet the flesh stay's nice and moist.