Depends on the steering arrangement. AIUI they switched from 4 degrees to 6 degrees when they went from steering boxes to rack and pinion.
I believe that most people (myself included) who have tried steering bearings and found negative effects have steep angle/steering box cars with relatively narrow tyres, and have removed the damper blades.
The modern cars with R&P and wider tyres don't seem to have any ill effects at all from fitting the bearings, and of course MMC dispensed with the damper blades some years ago now.
On my 4/4 (narrow tyres. 4 degrees, steering box) I am currently running the Suplex system with bearing and damper blades, and it's fine at all speeds apart from an occasional tiny self-damping oscillation at the traditional 'Malvern Dance' speed of 47mph. The easy solution is to go faster (or slower of course, but who wants to do that?)
