well i need to do more testing, i was lazy and just used my OSSC for now.
I tested booting up a gamecube and loading SWISS. SWISS loads in 480p by default.
The EL1881 on RGBHV was fine at 15khz then lost sync altogether at 480p
The GS4981 on RGBHV was not stable at 15khz (OSSC screen was flashing and sync rate was flicking around changing numbers) then when it went to 31khz it did the same thing, but it didnt lose sync like the EL, it just was unstable as hell.
Both were rock solid and fine using CSYNC (even CSYNC over SCART at 480p)