Support the hull better, but are a PITA to launch with unless you can get it in deep enough to float it off.
- the opposite of that!
My old SR4 was on a bunked trailer. Total @rseache to launch. Got the " new" boat on a bunk trailer - same thing. That trailer was well past it's use by date & is now doing service as a sdinghy club safety boat launch trolley.
I bought a swing roller trailer to replace it and I think in the last 5 years I've only had to un-hitch it from the car once to recover, and that only 'coz the slip was living up to it's name & I couldn't trust the handbrake. (people with 4x4s were also using ropes if that puts things in perspective!)
My thought, FWIW - if you launch & recover a lot, and / or use shallow slips a swing roller is likely going to be the preferred option.