i may be the only one doing this, but i'm actually going belt first. it's the biggest upgrade for me (still sporting http://www.wowhead.com/?item=45829). yeah i've been very unlucky with 25twins...
i'm still going back and forth between the two, but the trinket would replace http://www.wowhead.com/?item=48020 and that would just be too much lost exp... but once i get WFS or DW i'll try to also get HWT (hopefully will have enough frost emblems built back up by then). so HWT is definitely up there and probably the best choice for most people depending on their current trinket situation