I am just about to convert my bunk trailer to rollers.
I agree that bunk trailers are more stable when towing, but my problem is that every local slipway has such a gradual gradient i have to get the trailer so deep only the winch is out the water before she floats off.
Recovering the boat is equally as challenging. I have scratched my hull trying to get her lined up on the bunks.
And recovering requires a 30m length of rope to pull her up the slip.
My plan is to use the new rollers to self align the hull, but leave the keel rollers in place to try to spread the weight 50/50 between the keel rollers and the new hull rollers.