Another Steve here, I never use the Steb centres and have no problems with the standard drive. I would reccommend using a morse taper version of whichever style you pick. Unlike others I very occasionally sharpen mine on a small 6" grinding wheel, after many years this does mean you need to turn out the center to give enough clearance for the wings to grip the timber so for this reason I would not reccommend it unless you are happy turning metal. I have made a few centres from old drill bits. I have several sizes but use the 1" the most and find it will hold most sizes of timber. My largest is a 1 1/2 " and that holds fast almost anything.
I would never use a mallet with the timber in the lathe as this can't be good for the bearings. I have a strong tailstock on my lathes which create a lot of pressure easily.
I don't see any advantage of a spring loaded center and they are expensive.