AFAIK, the general "word" was the -38 would not work in the STE?, which does not hold true in my tests.
If there was a batch of actually faulty -38's when the STE's were made then that could be what jookie saw/had. Though as I have not had a "faulty" STE I can't say if the fix will work or not on the STE. If there is a blown pin on the -38's on the STE, then no, the mod will not solve that. Though other than jookie, I have not seen anyone else saying about actual faulty chip. People just seem to assume its faulty as its a -38 in a STE.
As for the circuit, the STE's DMA is almost identical to the STFM, with exception there are buffers on all the pins, EXCEPT the 2 pins where my caps go. In that respect the STE circuit is identical to the STFM. So any faults on the STFM are most probably on the STE aswell.
My 2 STE's work fine with the -38. AFAIK, people with hard drives have had random issues, not simply "dead" issues, but it is very difficult to obtain users results on it all unless more people get onboard to help with the stuff.
I had one revision STFM board which would work 50% of the time with a -38, but other revisions of board simply would not work at all, I could say in that case the DMA is dead, but the DMA worked perfectly in the STE. So that isn't the problem. The timings on the ST are all running borderline, a 1% tolerance on something is enough for it to either work or not work totally, thats how bad the ST design seems to actually be. Changing to the new DMA is "just" enough to tip it over back into the working state. This does not mean the old DMA is bad. Ironically the -38 could actually be a better chip as it shows up the faults
For me, fitting a new DMA in a STFM did not work, so the STFM has DMA issues regardless of what DMA chip is used. My mods fix that. Until someone comes along with a "iffy" STE to try the mod on, nobody in the world will ever know if it works or not. I myself simply cannot do anymore work here as I do not have a STE which has a "bad DMA". I have tried about 10 -38s in my STE, no problems at all. I urged people who replace their old suspected duff DMA with the newer one, to send me their old DMA for testing to see if it works in my machine or not. so far nobody has come forward and I posted that request some months ago now.
This is all why I urge people to document motherboard revisions, and try with and without the mod and report back. The mod may work for some STE owners, but not all. It could depend on the hard drive or the PSU, MANY factors. If anyone had a suspected bad STE, they are welcome to send it to me and I will test my Gigafile on it without and without the mod.
GadgetUK has mentioned many times already its solve his STFM problems with US, it solved my problem with GigaFile too. So that is 2 hard drives on the STFM which are now stable after the mod. MORE hard drives NEED testing, and MORE ST/E's.
We can all sit around and debate it for the next 10 years. So unless people get off their rear ends and actually try things out, then everyone suffers with these problems and will continue to do so.