I'm not so sure she needs to change tactics and go our harder from the gun, rather she just needs to start her kick earlier. She looks to make her move at around the 230-250m point. If she just started to kick that bit earlier and that little bit harder then that in itself would make a difference; indeed she would have won gold in London (ok, shoulda woulda coulda)
I felt she was lucky in 2007 that Williams didn't dip at the line; she could so easily have been the silver and not gold medalist. 2008 was better judged and 2012 wasn't quite right. To me, the 'simple' answer is to kick that little bit earlier.
She is a fairly even paced runner, that is how she runs, so to make her go harder from the gun I just dont see as benefiting her as she simply isn't fast enough. Also, she got out faster in at least one race last season (can't remember which but it was televised in the UK) and she still didnt win.
Until she gets her 200m PB down by at least another 3/10ths then she will remain in the same ilk as Guevara and Miles-Clark - even paced runners that give the impression of a strong finish when the others are faltering.
So, I would like her to work more over 100/200 this seaosn and start her kick at 200m and no later. Simples