Sandy,
As has been said the Efke films curl a little, but not as badly as Fomapan, I don't scan negatives except for low res images so can't really comment, and I have to admit that I mainly use the sheet film version of KB25 - PL25 now.
While there is a significant difference between the KB25 - 35mm and Tmax 100 in terms of grain etc I rarely use it now, best results are always with a tripod & I only shoot 35mm hand held, if I'm going to use a tripod then I shoot LF. I've really only shot a few rolls of R25 - 120 probably less tan 30 rolls in 30+ years, because I preferred the Agfapan 25 and then APX25 and I'm mainly shooting the LF cut film PL25 anyway
EFKE 25 is not fully panchromatic, it's about half way between Orthochromatic & Panchromatic. So on balance I preferred using Tmax 100 which I've used since it's release until the middle of last year, mainly because it's a robust reliable film and was once easily available off the dealers shelves. I've only switched from Tmax because I'm finding Kodak B&W films much harder to find than Ilford, Fuji & Foma, so I've gone for Delta 100 & 400.
My take on EFKE 25 is KB25 is superb for tripod based 35mm work with good prime lenses, and a big jump in quality over Tmax100 on a 20"x16" print, R25 - 120 is much the same you would get a decrease in grain etc on a 18"x24" print but the differences would be far less noticeable.
In sheet film sizes the major advantage is a very significant saving in material costs
It's worth trying a few rolls of 120, but the emulsion is soft and needs tighter temperature control during processing and extreme care handling when wet. You might decide it's worth it but you should also look at Pan F, but with a 6x7 Tmax 100 or Delta 100 are both excellent choices. I process them all in a little known developer Pyrocat HD
The best slow film available was probably Agfa APX25, the KB24/R25/PL25 isn't far behind.
Ian