Gardening and Horticulture - Formerly sick privet hedge now running amok!

I have a large privet hedge dividing my property from the one next door. Last year the hedge was doing horribly -- dropping leaves like crazy. My arborist has been spraying it for whatever bug has been causing the problem, and he did a reduction a year ago of some of the old stems. So far this spring we have had a lot of rain, and now the thing is going nuts. I am finally getting some growth at the bottom, but this growth is getting "leggy" and flopping over, and the top flops over when it rains.

Should I prune it? If so, how extensively, and when? And should I be careful of anything? I'm willing to manually prune instead of using a hedge trimmer if it's better for the plant.

Pruning by hand (manually) will give you more control over what gets cut and give you a less formal look. That would be what I'd do with the tender new growth that hasn't hardened off yet. I'd say to prune back by half the new growth. Cut just above a leaf node.
http://www.bbc.co.uk/gardening/basics/techniques/pruning_prunehedges1.shtml

You might also find this helpful about pruning. For hedges scroll down to their page 10 under 'Hedges, Espaliers, and Topiary'.
http://www.hort.purdue.edu/ext/HO-4.pdf

For future reference you might find these helpful.
http://www.taunton.com/finegardening/how-to/videos/trim-hedge-with-straight-edges.aspx

Newt

Privet can withstand brutal pruning, including down to the ground! It's the one plant that I don't mind taking the hedge pruners to.