I definitely wouldn't call it soft, in fact in terms of detail it's the same as the VT20 more or less: both can resolve all the fine details from a 1080p image.
A bit noisier? Perhaps, if you're sitting very close. The new 2000hz FFD distributes dither noise in the picture in a different way to the older panels. But it's nowhere near as noisy as, say, a Pioneer Plasma was.
My advice: try to see an ST50 in a store, put it in to the True Cinema mode, and experiment with the IFC setting to see if the motion is to your liking