It would be nice to have a double side on the existing single sided hedge trimmer. The single sided hedge trimmer have a better feel when cutting because the handle and the way you hold it is totally different from the normal double sided ones. I think the handle of the single is better and give a more comfortable and precise control. The problem with the single side blade is you can only cut in one direction. Branches grow in both direction and it is always cut better in either one direction sweep or the other. You really need the double side blades.

For gas clippers maybe some kind of governor to limit the engine/blade speed. Mine seem to cut best when not run flat out through light stuff. While you're at it make the governor adjustable with a thumb wheel on the handle.

One of my peeves was to maintain the hedge tops level with the horizontal lines of the architecture and NOT follow parallel with the grade, or adjacent street-side sidewalk. To do this, I set temporary strings with a line level and stepped the hedge tops at designated points along the sloping grade.

This was a pain to set up each time I trimmed and back then, wondered why tool designers never developed some form of built-in level system.

Think about ways to incorporate a laser system, whereby either a laser beam is integrating into the trimmer - aligning with some fixed horizontal reference line, such as siding courses. Or a smart device which can be set to a horizontal co-ordinate and emits a signal when drifting up or down from that set position.

How about a changeable gear box with different blade length? It might be out there but it should not cost a lot more. In fact, they should make the gear box cheaper because the blades do get blunt after a while, making the gear cheaper and turn into dispossable when the blade wear out. This will give the option of different blade length. You can have 30", 24" and 18" for final touch.

Forgot to mention, it cost $80 to $100 to sharpen the blades. Make the gear box cheaper by not putting in bearings ( Echo HC151 gear box is perfect example of a cheap gear box that don't have anything fancy and last longer than the blades!!). They should be be able to make the blade unit for less than $150 or so.

Otherwise, as I mentioned above, the users eye can follow the transmitted laser beam along a fixed horizontal element beyond - lines of buildings . . even the ocean's horizon, if the hedges have the good fortune to border waterfront property. ;)

You want to get the job done fast, it is not practical to set up a horizontal or vertical reference before trimming!!!! This is not precision work. Just trim, then check the level, then touch up if needed. Nobody can tell if it is within a few degrees!!!

While you are concentrate on the leveler, you might chue up the hedge accidentally if your eyes are not on where you trim!!!!

The OP (who hasn't yet replied) requested ideas for identifying design "problems" with existing hedge trimmers and creative solutions to these issues. I was simply thinking outside the box.

For trimming formal hedges, we all know that level guide strings, secured by long stakes, are typically used. The trimmer operator uses these lines as a guide to form (ideally) perfectly level and flat hedge tops - aligned with the earth's horizon, NOT the ground level. The line serves as a datum reference - w/o it, the tops will end up being uneven with buildings, which are also built to be perfectly level and plumb.

My suggestion of adapting a laser device - which for decades, has been accepted by land surveyors and builders as an accurate measuring tool, was intended to inspire the industrial designer with new ideas for hedge trimmer designs. Don't take it so personally, my friend ;-)

For detail work, a battery trimmer should be better....lighter. But I have not seen a higher voltage small trimmer yet. I would like a 12 to 14 volt one.

I forgot to answer your question directly. I think the cordless trimmer is very useful. Even it is 18V, it would be a looooot lighter than the gas engine trimmer. You are talking about 12 lbs. I don't know whether the battery ones will ever trim as fast as the gas but for finishing touch, it is very very useful.

I just planted a Hollywood Juniper and trim as a pom pom tree ( few poofs of green at the end of the branch ). It is going to be hard to swing the big gas trimmer around to trim this. Also I am planting 10 of the Boxwood at the back and going to shape it as a round ball of about 24" diameter. That you need a light short electric trimmer also. I don't think my low voltage Craftsman can do it. I need something of a 18V with about 12" to 16" blade. Make it less than 6 to 7 lbs. That would be perfect. Of cause, the lighter the better. Still interchangable blade will be very useful.

I never run out of battery yet. YOu can never have one trimmer fit all. YOu always have to have a gas for fast trimming and the small one for touch up. Don't think you can get the speed with a battery trimmer. Corded trimmer is absolutely out of the question.

I still think there are design possibilities with the Line Laser Level idea - perhaps the laser could be a remote device, that projects a horizontal level line across the top vertical edges of the hedge face, as a guide for shearing the hedge tops. It's certainly easier than setting up poles and strings - which sometimes get cut by the trimmer blade . . . in my experience at least.