Inverters do improve efficency quite a lot over both asynchronus motors driven via line frequency (those SQ used in their washers before or as you would find in dryers) and brushed motors (more found in EU FLs until recently).
The Inverter units (which basicly just act as voltage and frequency modifiers) got really cheap to make recently.
Even the cheapest of the cheap machines over here now widely use inverter motors.
For a lot of dryers over here it is an essential part to use inverter motors to reach A+++ efficency ratings (highest official class).
While the efficency gains are usually only in the low double digit wattage range, that still is 5-10% more efficent.
They are far more flexible, far more reliable then brushed systems over all.
And yes you now have 2 control boards in your machine; thing is that if you had a machine with variable speed motor, that control was either integrated on the main PCB (like on many ELux machines over here) or was a seperate board already (see the Neptunes).
Torque is much higher and verry consistent compared to brushed motors, they are much quieter too.
Keep in mind that noise is just another form of inefficency, though it usually results from other inefficency, mostly friction.
I wouldn't really agree on that bearing thing per se.
What wears down bearings more is load perpendicular to the axis of rotation or along the axis of rotation, but not rotational force.
The way machines can be more bearing careing is that for example on a frontloader, the high torque and verry precise rpm control allow for verry elaborate yet quick rebalancing strategies.
Best example from over here:
Before spinning, Electrolux machines with brushed motors turn once clockwise, then speed up to distribution speeds counter clockwise, take about 10sec to sense the balance of the load, then drop rpm to tumbling agin for 5 sec if needed, and repeat a max of 3 times before starting over again.
With pauses that gives you 5 tries in 5 min.
If they have an inverter, they do 5 tumlbles in reversing directions, starting out at a higher wash speed clockwise, increasing speed by 5 rpm every time.
On the 6th speed (after a minute or so) we are at distributing.
This pulled apart tangeled laundry somewhat allowing it to distribute better.
On that first distribute it dosent need more than 5sec to sense, then drops and restarts.
This allows it 5 or 6 tries in 30sec or so.
This means we still get 5 or 6 tries in 5 min, but have more distributions and a better distribution preperation.
Thus, out of balance boundaries for aborts can be set narrower, theoreticly improofing bearing life.
Or, on quick cycles, or on lower rpms, these cut offs can be set more precisley and more versatile.
