When I had finished giving my box hedge its winter trim on Sunday, it is that time of the year by the way, I decided that next time I would use a machine....
Indoors and over a cup of tea I had a rummage on the web and turned up an excellent summary of what to think about and look for on GardenVisit.com (an entirely excellent site by the way, full of really good stuff and the best garden visit planner I have ever seen).
It sort of breaks down like this:
If you have a small hedge, do it by hand, but if you have a larger hedge (or hedges) to keep tidy, then you will make your life easier with a power hedge trimmer tool rather than a hand tool. The choice then is between the relatively expensive but more powerful petrol hedge trimmers or the cheaper but weaker electric ones. Try to let the jobs the machine has to do determine your buying decision.
The first big decision is whether to get a double or single-sided hedge cutter. If you have topiary or shaped hedging, get one with a double-sided blade - it means you can cut backhanded as well as normally. However, if your hedging is predominantly long and straight, a single sided machine may be preferable. For the same weight you can have a longer blade meaning you cut more hedge inches per minute and the balance tends to be better making them less tiring to use.
Hedge trimmers do not float around by themselves. They weigh something and need to be carried while trimming. A heavy machine means cutting the hedge is a struggle and you end up tired, you run the risk of dropping it and it can strain your back. Weight is also a perception - a machine that is well balanced will feel a lot lighter (and handle more easily) than one that is not.
Two other - obvious - tips. Keep the cutting edges on the blade of your machine sharp - as with any cutting operation, the sharper the blade the easier and sweeter the cut. And wear appropriate protection. Gloves, glasses and ear defenders.