Seems so:
https://bikerumor.com/2017/08/21/review-efneo-3-speed-gearbox-crankset-makes-easy-keeps-clean/
https://road.cc/content/review/227796-efneo-gtro-3-speed-front-gearbox
https://forums.mtbr.com/internal-gear-hubs/efneo-3-speed-crank-934753.html
Link source:
https://www.bikeforums.net/folding-bikes/1211050-efneo-gtro-3-speed-crankset.html
Regarding Strida, it is for my meaning very good that I can be installed into all the older frames with the 60 mm bottom bracket - contrary to the EVO drive.
Is it good or bad to loose the pedaling backwards shift method of the EVO drive?
That will be mainly a matter of personal taste, right?
There is an additional shifting cable required for the efneo GTRO; please judge yourself if that is something you want to deal with or not.
The third cable will run most likely outside of the frame and it may interfere possibly with the steering lever clamp while folding - just this small flaw doesn’t count for me, I receive a convenient grip shift method in return 
Correct; usual rear hubs are not suitable because none of them does exist in a single-side mount version.
Yes I heard of that Shimano behaviour, unfortunately is my experience very limited because I’ve installed so far just two efneo drives and used one of them rarely due to lack of time for riding.
What do you mean exactly?
Cable issues can’t belong to a Schlumpf drive, these are available solely with heel shift (kick shift) switching mechanism, the actuator for the clutch is on this drives a steel rod - there’s no cable inside.
Nowadays, as the complete Schlumpf speed drive Strida kit is not any longer available, you would be forced to order a Schlumpf drive and beltwheel, belt and excenter separately!
I guess the costs would be in the end much higher than that for the efneo.
If you want to cut the costs there is still the compromise of the ATS speed drive kit:
https://www.bikegang.co.uk/bikeganghut/Strida-ATS-Speed-Drive-Crankset-Upgrade-Kit-Heel-kick-shift-2-speed-ATS-p49717138
But caution, the parts will be sent from outside the EU; most likely you have to expect additional costs for customs duty.