Braid is required if you have a level wind IMO.
Used on my Low profile Overheads exclusively.

On the non level wind O heads it's OK if you use round profile braid that is of medium to high quality and is 8 strand.

I find cheaper braid tends to stick when casting. It looks like it is bedding into its self due to the thinner diameter being able to slip in between already spooled line.

Can be overcome but requires higher management levels than mono when casting.

IMO only and at a purely functional level, Braid is a better option when using the O head for lure casting only.

For fishing with cut baits, I find mono easier and cheaper in general. Exceptions to this are when fishing areas with a huge current and where significant weed or lettuce exist. As an example, Tauranga/Mt Manganui seem to be better served by using braid when the sea lettuce is a nuisance.