Why do we have to "accept" anything? Why should we be in haste to pick a side? For a question this complex, a situation this novel, isn't the intelligent response to reserve judgment, to keep an open mind? After all, if Data 2.0 himself isn't jumping to a conclusion about who he is, why should the rest of us?
I think we're on the same page about this, actually. My argument isn't necessarily that he's the same. And I feel identically re: reserving judgement.
In the end, the only real answer for this is simply going to have to come from Data himself. Personally, I don't think either answer is right. He isn't the same being as he was before his death, but neither is he something completely different. It's going to be up to him to decide what and who he is now. It's not really our decision, it's his.
After all, going back to the Farscape example. Both John Crichtons decided they were the real Crichton, and the show never gave us any reason to believe either was wrong, even if it's mathematically nonsensical. But by contrast, when Will Riker was twinned in essentially the same way, we know who the 'real' Riker is, and to an extent, even the characters seem to recognize that. As it should have been. Identity is as much a personal choice as it is a product of your creation. We can argue about it as much as we want, but in the end, only Data can decide whether or not he's 'real' or whether he's Memorex.