I have several keyless 1/2" chucks and they work real well in general use. If I'm punching through thick heavy metal on the mill, I would usually switch to the keyed chuck for a little more holding power.
This is why when I buy a cordless drill, I always buy the one with the hammer option, even though I have no need for a hammer drill. The ones with the hammer option always have the better chucks with better holding power.
One thing to look for in a keyless chuck, are carbide teeth that give some serious grip on a bit.
I purchased an all steel keyless chuck on line for my mil-1/2 hammer drill. I hated the old keyed one and could never find a proper key to fit it. The teeth finally tapered and wore out on the old one.
One of my all time favorite auction finds was an old 7/8" keyless chuck made in Turkey. It was pretty nasty when I got it, but after a lil love Ive done some serious hogging on the lathe with it. Until I found this thing, I never knew they made keyless chucks that big much less wouldve believed they worked so well. To date, its never had a bit spin in it.
Only have keyless chucks in my alzmetall drill presses and use them with success for drilling into steel up to 0,5 in. I use the Rohm or Albrecht type keyless chucks but in my opinion the original ones made by those two companies are too expensive.
Look for cheaper copies for exemple made in poland, these are quiet cheap and very well made. I use those copies since years now and could not notice a difference to my Rohm and Albrecht chucks in daily use. Sold all my german made chucks and bought about the double amont of no name chucks made in poland in new condition. Same performance for half the price.