I had problems with 4.28. HDTach and Scandisk both generated DMA errors with these drivers. I reverted to 4.26 until 4.29v(a) (now just 4.29) became available. No DMA errors with this version. AGP 4X is stable. Those are the only issues that I have had with Via 4-in-1 drivers. Now they are both resolved.
I'm using Windows 98SE an Abit KT7 motherboard. Results may be different with other boards and other versions of Windows.