I keep thinking that the only mechanism that Epicurus (not Cicero, the Cow) explicitly provided for ranking, prioritizing or choosing/avoiding was desires. He seems to me to keep saying that "pleasure is pleasure", a pathe. Why else would he repeatedly make the point that if all other things are equal (condensing/accumulation, duration, location in the body and so on) then pleasures would never differ from one another?
There's no doubt in my mind but that this is a very challenging passage.
In my mind, the first part of what you are referring to there " pleasure is pleasure" arises from the conjunction of the feeling and the definition - we have many different types of feelings which are knowable to us directly and without rationalization, but our decision to give them a single name ("pleasure") is a conceptual decision.
As for the hypothetical that if the pleasures could be condensed to fill the whole person then they would never differ from one another I better yield to Don since he is master of the hypotheticals!
However if I were to go ahead rather than wait for Don on PD09 (PD09. If every pleasure could be intensified so that it lasted, and influenced the whole organism or the most essential parts of our nature, pleasures would never differ from one another.) --- I would say that the point most likely is again some conceptual point of contention (probably with Plato) because I believe that Epicurus would say that the individual experiences of pleasure cannot be so intensified, so that observation of the reverse proves something (perhaps indeed the connection of the experience of pleasure with the particular part of the mind or body. I base that in large part on the presumption that it would be a core premise of epicurus that pleasure does not exist "in the air" but is an emergent property of particular living beings.
As to PD09 I seem to remember DeWitt asserted something about that so his suggestion is probably worth going back and looking up.