Our feeling about this is that anodes work in line of sight and there are limits to how far they can throw current, so having a big, thick, short anode at the top of the heater might not protect the bottom so well as a longer, thinner anode.
Of course, we try for both longer and thicker, to put the anode nearer the bottom of the tank and also to have the maximum amount of anode metal inside it.
As to your current anode, the choice is yours. We don’t often push people into a decision where we benefit. There is a clear conflict of interest there.