Delayed Reaction and Neotac's Control-It are different from most products in that they contain something usually called a "slipping agent." They bond to the ball surface and contribute to additional length and a DECREASED back end reaction. Once on a ball, they need to be removed by sanding (or simply being worn off through long use). I have not used Ebonite's Extender Ball Polish, but I don't think that it contains a slipping agent. I believe it increases length primarily by polishing the surface so that the ball can go longer and save its energy for the backend. If that is the case, it is quite a different product than the first two mentioned. Those first two increase length and kill the backend as well. Most polishes don't act that way.
I've looked at the Ebonite website, and it doesn't specifically say whether Extender will contribute to a decreased backend like the other two. It is probably worth contacting Ebonite to find out.
Shiv
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Listening to the monotonous staccato of rain on my desk top