There are screenshots that shows a ridiculous 5 btc buy support.
When btc spikes nubits and co have a big liquidity problem and it is only getting bigger the more btc rises.
Just think about it and hope they dont run.
There will always be screenshots of such.
Some might be fake, but there are real ones as well.
I can only speak for Nu, because I'm not familiar with other "stable" coins.
Providing liquidity for Nu comes with some safety measures. In very volatile times it might happen that walls are pulled for a short period of time.
But it's necessary to do that. Otherwise you might end up selling 1 NBT for the BTC equivalent of $ 0.9 (in case the BTC price swings down by 10% in a short period of time while the wall doesn't get pulled).
There's nothing wrong with that. Selling 1 NBT for $0.9 and buying it back for $1 is economical suicide.
I understand that people are unhappy not being able to profit from misplaced walls...
As soon as the volatility settles, 1 NBT can be bought or sold for $1 (+/- exchange fee and a little buffer to prevent the walls from being shifted at each tiny move of BTC price).
NuBits have been stable for more than one year (even being under pressure with exchange hacks in February this year), are able to handle daily trading volumes of millions USD (have a look at January this year). The recent daily trading volume was hundreds of thousands of USD. The peg was kept tightly all the time.
If you want to have a live overview of walls maintained by Nu, have a look here:
https://alix.coinerella.com/walls/Of course there's not one exchange with all the liquidity - Nu is decentralized even in this area.
Seriously - what are the alternatives?
Trading to real USD (or other fiat) at an exchange which you are not able to withdraw in minutes and send them back in minutes 24x7 (and only after you have passed KYC etc. barriers)?
BTC-E coupons or alike?
USDT (Tether)? You are aware that Tether is fully centralized by holding the collateral in USD? If the funds get frozen or lost for whatever reason, USDT is worthless.
bitUSD is open source and distributed, but has little (currently: no) volume at exchanges. The spread is much closer since the release of BitShares 2.0 - it's yet unknown how it can handle high volumes on exchanges. Have a look at the number of supported exchanges and the trading volume:
http://coinmarketcap.com/assets/bitusd/#marketsAnd you complain about "only" 5 BTC buy support for NuBits at a certain time?
coinoUSD is based on NXT, but a fully centralized Coinomat operation. It requires proxy assets to work, which doesn't make using it very convenient.
MØ is closed source, distribution status is unknown (to me) and the inner workings seem to be hidden behind marketing names like "Argus-Nemesis algorithm", "Clotho-Hydra algorithm", etc. - come to your own conclusion!
NuBits is open source, distributed and based on well-known software (ultimately based on Bitcoin code, with Peercoin and Peershares in between).
If you want a stable, blockchain based, open source, decentralized, pegged (to USD) currency capable to handle decent volume and without external collateral, the choice is somewhat limited at the moment