Setup: A600 with ACA620/16 MHz and 3COM PCMCIA running latest Roadshow68k.
The latest I had tested before was 4.0-2016R1.
I've gone 3.8 -> 4.0-2016R1 -> 3.8 -> 5.0-2016R3. iBrowse 2.4 is working fine, but I tested it only for 5-10 minutes. If I should complain about anything it's the fact that the default fonts are clearly chosen for modern screen resolutions, not ECS low-res.
So iBrowse 2.5 in combination with MUI 5.0 (both in 020 versions) should probably be fine.