Over The Top Environmental Activism?

Environmental issues can certainly stir up a lot of strong emotions and actions; but I sometimes wonder if there is a tendency to push things a little too far and perhaps do more damage to a cause than good.
Last week, Greenpeace protesters broke into a CSIRO experimental farm in Canberra and destroyed a crop of genetically modified wheat with whipper snippers (weed whackers). The Commonwealth Scientific and Industrial Research Organisation (CSIRO) is Australia’s national science agency.
I’m no fan of frankencrops, something I’ve made pretty clear over the years on Green Living Tips, and a part of me said “bravo” to GreenPeace’s action; but a bigger part thought “eek!”. This goes a little beyond chaining yourself to a tree – there is trespass, break and enter involved and the destruction of property.
The action followed news that CSIRO is conducting the world’s first human feeding trials of GM wheat, without adequate safety testing according to Greenpeace.
I can understand Greenpeace seeing this crop as a clear and present danger. I can understand how they would see this action being fully justified – but many people not familiar with issues connected with genetically modified crops wouldn’t. 
Many still fall for the old line of GM being just like selective breeding (which it isn’t) and would see such drastic action as ecoterrorism (as much as I hate that word). 
I keep tabs on the farming community in Australia and a lot of the comments I read after this incident were very critical of the action – and farmers are an important group to win over in the battle against genetically modified crops.
By the way, this action wasn’t carried out by big burly dudes or spaced out hippies – three moms were the wielders of the whackers.
One of the group, Heather McCabe commented, “I’m sick of being treated like a dumb Mum who doesn’t understand the science. As far as I’m concerned, my family’s health is just too important. GM wheat is not safe, and if the government can’t protect the safety of my family, then I will.”
I can understand her concerns. I’ve been tempted at times to take more direct forms of action on environmental issues; but the law and the possibility of unintended and possibly tragic consequences keep me in check.
The action of these three women certainly generated a lot of publicity and it was the first I had heard of these intended trials. But does the end justify the means? Given the success of drawing attention to these trials through the action, I fear an escalation in the number of similar incidents and that at some point, someone is going to get hurt. 
My other fear is these sorts of approaches will begin attracting the wrong sorts of people to environmental groups – those who enjoy this sort of activity purely for the sake of destruction, but carried out under the guise of concern for the environment. 
What are your thoughts – should environmental issues be pursued so aggressively?