Looking through all the different spindle options one inevitably finds a couple of wonderful Metabo offerings.
The 1.4kg 710 Watt Electronic Router and Grinder Motor, FME 737, would take some beating in the capability to weight ratio stakes.
The unit has Metabo's famous Vario-Constamatic full-wave electronics, I used this on what was my Fathers most treasured tool, now my equally proud son's drill. You dial up the speed, half press the trigger till the rear lights indicate its ready to go and then with a full trigger press its constant speed no matter the material. With my brother included the four of us spent an hour or so merrily drilling away in pressure cured traffic-able manhole covers when Dad first got the machine - amazing stuff. I doubt if there is a wait now on the newer tools like this router motor.
My brothers slightly smaller clutch-less version of the same drill threw him off the roof when using it to put in roofing bolts - not as much power as this FME 737 router motor either, just set to lower gears. Metabo is beautiful gear, the bearings and collets on this motor are similar to the Proxxon standard of their ib(s)/e, just bigger and longer lasting.
On the non constant speed or standard speed control end Metabo have a G 500 die grinder, again 1.4kg, with a full load speed of 16,000 revs at 500w.
The price of these Metabos, fme 710 240v around au$350+ and the g500 240v au$300+. For our fine young Americians, the g500 110v is on Amazon for around us$180 (couldnt find the 737), with the Ozzie dollar at parity I might just look at getting a step-down transformer.
I own a 2400w Router, a Triton, its a monster - but from the Metabo tools I have used I bet these two small Metabos are just as impressive in their own way. As you may have gathered - I believe a good ramble clears the soul.