We have ben using swing back blades since 1948 the first domestic rotaries down here all had swing backs and have remained doing so ever since.
Honda walk behind models for Australia & Europe also use swing back blades .
All of the slashers (rough cut to some ) available down here except the ones directly imported from the USA use swing back blades.
All of the 3ot linkage rotary mowers for real tractors use swing back blades , if you can call a 1/2" to 1" thick length of steel a blade .
Flail mowers use swing back blades
The locally made ride ons all use swing back blades and some badge engineered USA ride ons got converted to blade discs & swing backs .
We even make conversion plates & bars to convert bar blades fitted to USA imported domestic walk behinds & ride ons to swing back blades.
I have converted around 15 mowers to swing back & the customers have never stopped thanking me. They get a much better cut and no longer have to spend more time picking up gum tree branches than they do mowing.
And never have to replace spindle bearings.
The acres of manicured lawn types have bought rakes and find mowing first then raking the branches is a lot faster than trying to rake through long grass.
If I can just get them to stop mowing at 1" to 2" then my life and their life would be so much easier.
But some twit posted on U-BOOB that the natural preditors for snakes can not see snakes hiding in long grass ( total tosh ) so now all the city working lifestyle clots cut too low so the Kookas , eagles & hawks can see the snakes in their yard and eat them .
Must work because they have not seen any snakes , which is no surprise as they leave between 4 & 6 am and return between 7 & 9 pm then sleep in on the weekends .
A 3 blade set up is interesting.
Keeping the 3 blades in balance would be a challenge