If it is a transfer for potential CGT liability only it may not be worth it, but there are other potential benefits. If you die and you and your wife are named as joint tenants, she need only send in your death cert to the land registry and ask for your name to be taken off to sort out the title. If its in your sole name, she will have to extract a grant of probate to the estate. The cost of a grant of probate will be much more than the cost of a voluntary transfer now. It also adds certainty to her entitlement if you havent made a will in her favour and you have children as she is not automatically entitled to all your property in those circumstances.
However if you seperate in the future, and you have transferred into your joint names there is a presumption that she is entitled to half, even where you have funded the investment property entirely by yourself.