Wire halyards are good for out and out racing, where you never reef and the virtually complete lack of stretch allows good control of the luff tension via the cunningham; without the head of the sail ever budging. But they are a pain to manage, and apart from the the obvious issue of them fraying the rope tails tend to get damaged too and need to be re-spliced fairly regularly.
If replacing with dyneema / excel (or whatever) it’s worth leaving a bit of spare length on and then shortening the top end by a few inches every now and then. That avoids the jamming cleat wearing the same section of rope all the time until the sheath frays. Also, after the tail leads through the alloy jamming cleat I have a plastic horn cleat as well, so I can jam off the halyard as I’m pulling the sail up, then belay it round the horn cleat as well. This removes any possibility of it slipping, and also reduces wear on the sheath.
Apart from reefing, another advantage of a rope halyard is that it is much easier to get the sail down in a hurry, if needs must. Trying to unhook a wire halyard from a toothed rack in a hurry is a nightmare, and what usually leads to fraying damage either to the wire or the tail.
If you do go for a wire halyard, one good solution is to use a highfield lever to pull it up rather than a rack. Seems un-necessary but it doesn’t half make life easier!