As far as encoding goes, an i3-6100 and FX 6350 (slightly faster than 6300) are tied in Handbrake benchmark.
http://www.anandtech.com/bench/CPU/1052
However, a G3258 OC'd to 4.4 GHz is actually a little better than an i3-4330 in Handbrake. The i3-6100 is a little faster and newer, but not hugely so.
http://www.anandtech.com/bench/CPU/1052
I can't really say how overall multi tasking ability will compare, but purely based on encoding, I don't know if you'll see much of an improvement either way.