This is true but they have to be in a block later. This part is interesting.

And please answer cryptonewb's post too 'cos he's way ahead of me

@cryptonewb, as far as I know if you try and make a double spend of an input the same masternodes will be selected to process it but I'm really not sure, more reading up to do :/ They don't get fees though, they're paid a percentage of the block rewards rather than on individual transactions.

I watched the vids. I'm still not sure how InstantX manages to be secure though...
I kinda understand how it works, but not sure how the security works.

This is how I think bitcoin works:
the big problem in cryptocurrencies is that there is lag on a network. If there wasn't lag, we could just all send transactions. Everybody would see the first transactions and an attempt at double spend would be automatically ignored.
But there is lag (latency) on a network, so we need some kind of synchronization. Therefore, bitcoin groups transactions in "blocks". These blocks are propagated in the network. Once a block is mined, the transaction has one confirmation. However, it's still possible someone mines on an older version of the chain, so for bigger transactions, it's better to wait for more (2, 3, ...) confirmations to be sure it's included in the longest chain.
(correct me if I'm wrong)

This is how I think DASH works:
There are decentralized oracles that are deterministically chosen and vote on "locking" a transaction. When the oracles decide that a transaction is locked, miners can't mine a double spend because all nodes (masternodes or all nodes?) reject transactions that are in conflict with the locked transaction. If a block is mined with a conflicting transaction, that block is rejected by the nodes and other miners (but how can you force miners to reject a block? ).
Also, I'm not clear on what happens with the double spend transaction if that one also get locked by other masternodes that ignore the first transaction. After all, your masternode get a fee when you vote for a transaction (I think?), so you have an incentive to vote for the double spent transaction. is it possible that there is a competing locked transaction?

So as you can see, I still have some questions about the security of InstantX. i marked them so it's easier to address them.

Are IP addresses logged? Maybe users of the site could save what they pay on VPNs and donate that to the site.

I can see that it seems to be users of the site that are in favour of the budget proposal. I don't doubt that the site provides a more convenient way of voting regularly than any other current method, but I don't think it warrants recurring payments, albeit only 6 months, as in 2 months there could be a better solution. I don't think a centralised solution should become the defacto standard. Nothing was promised to Dashwhale before embarking on the project, was the initial intention always to offer for free at first and then go after funding?

I'm not really interested in mining anyway, but the issue was that there were too much coins distributed in the beginning?
Was it a big amount? I see on coinmarket cap that currently there are about 5.9 million DASH in existence. I also read somewhere that there would be 22 coins eventually. Are these numbers correct?
so DASH started in january 2014 according to the blockchain (I checked block 1 here: https://chainz.cryptoid.info/dash/block.dws?000007d91d1254d60e2dd1ae580383070a4ddffa4c64c2eeb4a2f9ecc0414343.htm)

So it's (12+9) = 21 months old, that's about 5.9/21 = 0.28 million coins per month.
As long as the number of coins in the first hours isn't more than 0.28 million or so, i'm not really worried. That would be the equavalent of "one fake additional month"... Is there a chart somewhere on the history of the number of dash in circulation?

My thinking goes this far.  Instant Transactions will have the input funds locked by a set of 10 masternodes chosen deterministically.  There are 3,500 masternodes.  Therefore 350 (3500/10) Instant Transactions (minus overhead) can be locked simultaneously.  If this process can happen a couple of times every second, then 500-1500 is the answer.

If there are any devs watching that want to correct me, please do. 

Add width=x to the image tag to shrink images. Above I used width=200

I'm replying to you TanteStefana but I made a mess of the quoting so I'm going to leave it like this.

A little Doctors advice !


 

https://www.dashwhale.org/p/dashwhale-basic

There is a discussion there.  I implore anyone with an MN to participate in the discussion.  It's not just about this proposal, it's setting a dangerous precedent IMHO.