Sucks to want to experiment on tinkering with the power grid unless you screencap the page. I wish we could save it as a preset so that if our new build ends up bad (or you just wanna swap between different saved options) you can just hit a button to undo it.
I think for balance purposes and avoiding people switching mid-fight, you can only load builds in town or other safe zones.

Best recent example: I was fooling around with a weretiger build; it was a great build, but I was getting a bit tired of just holding left click all the time because I didn't have any other active skills (minus a roar here and there), so I wiped the grid and tried a new tweaked version of the build involving that vampiric slash move. I built out the whole grid, liked it, then found out that you can't do that slash while transformed. Oops.
Took me like half an hour to get my power grid back to how it was.