The extremely ambitious XND development plan was released last year, under the DarkNote appellation (*looks for citation, grows lazy, gives up*).
I'm pretty sure that is
incorrect correct (i.e. it happened after the duckNote->darkNote rename and after most of the fastmine was already burned out), and the first announcement of any development plans and new features such as encrypted messaging was simultaneous with the darknote launch. See for example
https://bitcointalksearch.org/topic/m.8892752 . I can't find, nor do I remember, anything earlier, and I was (and am) somewhat of a fan of ducknoze's quirky marketing, so I think it is fairly likely I would remember.
My hypothesis (totally unproven, but consistent with the history and a rational analysis of motives) is that they wanted to see whether they could accumulate a huge stash of cheap coins in the first few months of fast mining before revealing anything. If unsuccessful they probably would have just launched another coin instead of the rename/roadmap.
If you do, then I'll point out that XMR's (magnificent) plan for "enterprise grade" scaling wasn't posted until almost a year after launch.
Yes the difference is that 80% of the coins (or whatever the actual number is for XDN, I don't exactly know) were not already mined.
Furthermore, the Monero project operates (and has always operated) in the open, consisted of people with established reputations (and who didn't know each other), some with real-world identities, and was always open to new participants. It was always stated transparently that the goal was to operate as a long-term open source project and develop the technology in an open-ended manner. The idea of some sort of hidden agenda where plans were withheld in order to take advantage of a cheap coins from a fastmine just doesn't pass the laugh test.
Ducknote/darknote/digitalnote, by contrast, as far as we can verify, consists of one forum nick called dNote with zero history, zero reputation, and whose actions are is entirely consistent with a manipulative scheme to accumulate the bulk of the coins before revealing any specific or significant plans (exactly the same process of disclosure used by x-coin/darkcoin, an equivalnce you seem to want to ignore). If and when the project goes bad or simply fades away (once the fastmine coins have been sufficiently pumped and dumped), the entire reputational cost of that will be one burned forum nick.
I'm really surprised that in this intensely competitive and adversarial environment, someone as astute as you doesn't seem to understand that prudent investment requires interpreting actors and actions in the least favorable light consistent with verifiable facts, and that creating actionable investment situations requires presenting things such that the least favorable light is still favorable. IMO it is clear that Monero has done this, and dNote has not.
Finally, a three month mining period is not the same as a three year mining period. Such a difference in magnitude is a difference in kind.
Rather than bitterly holding grudges
There is no grudge and I don't really care what dNote does. However, this is a thread for discussing altcoins and specifically altcoin investments an in objective manner, so I'm going to comment on process and incentives, which IMO make dNote (and any other coin operating in that model) an unfavorable and unattractive investment story.
Short term speculation, who knows. If anything pump-and-dump coins can be excellent speculation plays if you can time your own trades to front run what you think the insiders are going to do (difficult, but not necessarily impossible). I think rpietila made this observation about Bytecoin fairly recently
EDIT: First, I misread your post as stating that the roadmap was under duckNote, but I corrected that above. I've now reviewed 100% of dNote's posts prior to the rename and found no evidence of a roadmap prior to the duckNote->darkNote rename. Further, I reviewed the state of the duckNote web site prior on archive.org immediately prior to the rename and found only this roadmap, which shows little to nothing of substance.
1. Improve High Level API
2. Implement GUI wallets
3. duckNote payment services
4. duckNote payment modules
5. duckNotej development
6. duckNote mobile wallet development
7. Community support
8. Media support
Since the first block i pointed with white rabbit and Bruce Lee and A.Huxley and W. Blake to understand that duckNote is much more serious you can think at first.
Not to concentrate on a finger.
http://archive.ducknote.cc/I`ve seen this ASIC mining races, i`ve seen that gold rush in their eyes.
1-CPU-1-VOTE that is how it should be.
Cryptos is about voting, fair voting. And Free market, but not mining mining mining and ASIC-GPU-CPU-Botnet rat races and energy waste.
Have you heard about "Helicopter Ben"
?
Bunch of coins on a free market, lets make it wild, lets make it natural, let them be free.
@smooth your opinion of DigitalNote XDN formerly known as DarkNote XDN, formerly known as duckNote XDN is completely wrong, and you know that. Also you do interested in it, just a bit, i think
Speaking as a developer, i can say that XMR has a comparatively slow development and XMR has much less features and improvements than XDN, that is just a fact, please, don`t let me count it, you will be upset.
And i will end here with a quote for you again, to understand my point:
I must Create a System, or be enslav'd by another Man's; I will not Reason and Compare: my business is to Create.
William Blake
One of the reasons why I keep an eye on it - it sure is entertaining. 
