That's one of the reasons I'm going for a Tanaka. They are quite light. The one I am looking at weighs just under 5kgs. And as for the power... I reckon the more the better. I can see what you're saying though nota. Like I said before, I probably could easily get away with a smaller machine. I love my toys though! Thanks for your thoughts nota!
From a novice beginning (and please can the experts correct me if wrong) one of the things I've been told is that you can't 'slip the clutch' aka use partial throttle - its either full-throttle or idle-revs, and nothing in between so it's 'all or nothing' otherwise you risk burning out the clutch.
By this I mean it can be difficult to be subtle with a high-powered machine, when it comes to lawn & garden 'trimming'
Another mate was very impressed with my big powerful snipper and requested I come around to trim up her flower bed of errant grass & weeds. So I jammed it into the car, went around to her place, and proceeded to virtually destroy her prized floral display at maximum revolutions! Like I said, bits of petals and sundry were flying everywhere despite my best efforts at control, it was genuine horticultural mayhem. However I did manage to brutalise a small tree.
And that banshee wail of the engine at peak revs reminds me of the worst sounding 125cc 2-stroke sports-type motorcycles, with el-cheapo Power-Pipe etc. The engine doesn't purr, it just hammers. The Mitsubishi-powered engine of a colleague's KAZZ snipper sounds far quieter, smoother & less gauche.
As a car enthusiast I can well relate to what you mean about 'more power = better' and used to believe it a maxim of all things involving internal combustion. However I have found this is not always the case in practice.
Btw my hefty Shindaiwa weighs 'only' 5.4 kg .. choose carefully.