What "sources" said you wouldn't have to revert back to nodo before upgrading to the official mango? And by "sources" i don't mean "random wpcentral/xdaforum poster." I think it has been made very clear from the start that if you upgraded to the dev version(s) of mango, you would have to downgrade to nodo when the official version came out. As for that leaked "official" version, who knows?
As for me, I always new I would have to downgrade to nodo after I used the dev version of mango, but it's been completely worth it. It might take me an hour or two to get my phone set up the way it was before after the transition, but I've had mango for months now, and loved every second of it.