Cicero is speaking through Velleius, and using him as a literary tool, ultimately to persuade his audience to his cause, not necessarily provide an objective survey of history. So, I think that anything that the character Velleius proposes in Cicero's narrative needs to be referenced against the established doctrines set by Epíkouros and preserved by Philódēmos. There are a few things Cicero records that are surprising, so I read him cautiously.
Eikadistes I agree with this general concern, but as of yet I have not (to my memory) run into anything spoken by Velleius that I have found reason to question as being in actual or potential conflict with any other authoritative texts. Have you seen anything in particular to question from that section? If any occur to you over time and you remember this thread I hope you'll point them out so we can include those caveats in future discussions.
I'm with you there. I think my primary criticism is with the authenticity of the characters' arguments rather than the coherence of the arguments. Overwhelmingly, I like what he has to say. For example, his characterization of mythic gods as "world-builders" who may have suffered from ennui, or found themselves alone in an infinite dungeon of darkness, reminds me of the critical tone Diogenes takes against the cartoonish depictions of "god". I particularly like this critical approach.
I wonder, however, if these observations reflect statements made by Epíkouros, himself, anywhere in On Nature or another text, or whether these are comical inferences (though coherent) made by a later admirer? Or else, here again, are the amusing examples described by Velleius poetic devices employed by Cicero to shape his character and enliven his text for readers? I think a sympathetic reader would find Velleius to be an enjoyable character, and I would personally wish for this likable depiction to reflects a real, likable personality from history. Though, I could also see how an opponent might find Velleius to be disrespectful or mocking, in which case, the characterizing of Velleius as mocking by his opponents (if that's how you read it) might have been Cicero's way to discredit his opponent by associating their philosophy with jarring behavior.
For example, with his discussion of the composition of the "blood" of deities — that seems (to me) like it may have been a point of fascination with Cicero, or his readers, but I'm not sure that the Epicurean philosophers had interest in the topic of "god blood". I haven't found discussion of "god blood" in any of the Hellenistic texts. This could potentially be a strawman argument to make Epicureans seem like they represent their positions in a ... cartoonish (?) way. Velleius at a point seems unable to further elaborate upon his argument, and resorts to justification by authority (which is not one of the three criteria of knowledge): "Though these distinctions were more acutely devised and more artfully expressed by Epicurus than any common capacity can comprehend". Or, I may be treating the characterization unfairly. I'm just suspicious of it as a literary tool or a rhetorical tactic.
I've been thinking about it kind of like this: imagine one philosopher shows another the spatter from someone getting shot in a video game. They point at the screen and ask, "what's happened?" The other person probably wouldn't say, "oh, well our eyes are observing the images generated on the LCD screen from optical output rendered in a computer..." — they'd say, "That's a kill streak. So bloody..." Now, of course, they wouldn't mean, warm, sticky, real blood from a human animal in need of immediate medical intervention, they'd just mean "the comic violence that just happened on-screen". ... now, imagine that you personally walk into a room, expecting to hold a symposium with two friends with opposing philosophies, and the topic of conversation is a heated discussion over ... the "reality" of the cartoon blood ... and both sides are passionately engaged in the argument ... well, I might roll my eyes and wonder "Is this the caliber of thought I'm dealing with?"
If I'm Cicero, and I want to convince undecided voters that the attractive, rational, Epicurean position is false, I might try to associate the position with figures who gets caught up on ideas like "god blood". That's not to say it's incoherent. I think a huge part of Epicurean theology was to demonstrate that the images of the mind are all "real", just not necessarily "true". Breaking down, however, god bodies into amalgamations of organs, and not eidola, seems like it could be a kind of red herring or else a sort of scarecrow from Cicero. ... or not, but, I'm suspicious.