bsdimp
It's what I'm using and it seems fine so far. Looking at the schematics, it looks like there's good voltage regulation for all the critical voltages in the system. The 26V power supply for at least my old system is used mostly to activate the valves in the system, and a bit to run the PIC / microcontroller in the old system.
The issue that I've hit is that my old sprinkler only has 300mA and the spec calls for 750mA. I have another power supply for my Rachio, but I don't want to cut the end off if I can avoid it. It's looking like there's a bunch of cheap ones on Amazon if the 300mA one has stability issues.