I wouldn't start stacking haste at your level of gearing - on paper its a better stat but it depends how much you can stack without gimping your other stats. For most people pre-SWP then you can achieve just as much DPS through crit/damage gems (hey, as pointed out many times its worked for such luminaries as Buzzkill). Its only when you can stack significant amounts of haste without affecting other stats that it becomes worthwhile - for example if your choice is 100 damage or 100 haste (as long as the above is true) the actual DPS you can is very, very similar.
Timbal's is generally not as good as the Icon unless you're affliction in which case it has enough DoTs to proc from that it comes out a little ahead.
My advice is to check your stat weighting here:
WoW Warlock DPS Spreadsheet
and to read through one of the haste vs crit threads.