Thanks a lot for the responses. Seems like BitFury already admits that BitShares is not vulnerable to most of the attacks they listed. So the BitFury report is very positive for the BitShares community from my perspective.

They say this about the Long Range Attack.
"In delegated PoS, an attack typically re-quires collusion by 2/3 of delegates"

Is this a risk for BitShares when 2/3 of witnesses collude then?
Can you provide more detail about TAPOS and how it prevents collusion? 

Any comments/links relevant to the DOS and Sybil attacks?

I noticed this table on page 16:

Table 2: Vulnerability of proof of work and proof of stake consensus mechanisms to attack vectors

Attack type                                               PoW              PoS               Delegated PoS
Short range attack (e.g., bribe)                       −                  +                            −
Long range attack                                         −                  +                            + 3*
Coin age accumulation attack                        −                  −                             −
Precomputing attack                                     −                  +                             −
Denial of service                                          +                   +                            +
Sybil attack                                                 +                   +                            +
− −
Selfish mining                                          maybe               −                            −


So I think this means BitShares has vulnerabilities for Long range attack, Denial of service & Sybil attack only according to BitFury. And the point 3* says Long range attack can be prevented by using social-driven security in addition to protocol rules. 

3.8.3 Long Range Attack
Short range attacks described earlier in this section are made expensive in the case of delegated proof
of stake, so we need to consider the cost of long range attacks as well. For proof of work systems, the
cost of a long range attack is prohibitively high. For example, an attack on Bitcoin lasting for 1,000
blocks would require $4 million at very least (and, unlike a short range attack, it would be highly
visible as observed network hash rate would drop in half for an extended time).
In earlier versions of proof of stake, the cost of a long range attack would be much lower; as we
showed in the previous section, a one day long attack may cost about $5,000 in a system where a valid
blockchain is determined based on total destroyed coin age. In delegated PoS, an attack typically re-
quires collusion by 2/3 of delegates; its cost is difficult to assess, as delegated PoS protocols use differing methods to select, reward and punish delegates.

5 Conclusion
....

A recent development in proof of stake are delegated systems. While these systems solve several
major problems with the straightforward PoS implementations, they are not yet widespread, making
it difficult to evaluate their security. Nevertheless, delegated PoS solves the “nothing at stake” problem
and prevents short range attacks on the system.

Neat.
Thanks again.

I want to trade BTC:USD.
There is not enough liquidity in BTC:USD.

Can't the network also utilize the BTS:BTC & USD:BTS liquidity?
So the BTC:USD market is actually a merge of BTC:USD + (BTC:BTS * USD:BTS)?

That is not true . I fact , Bitcoin dilution grew a whole industry ---- mining that is on the front line of promoting bitcoin .

I agree. But the main point of my post was that bitcoin miners do not compete on that basis. They compete on the basis of mining power. Whereas BitShares delegates compete on more levels.

I read the paper posted at
https://www.reddit.com/r/BitShares/comments/3dhxda/self_managing_using_adhoc_random_boards_as_a/

There was a section therein which described crowd funders maintaining control of funds using a protocol of randomized juries. This sounds excellent especially since control is weighted by Stake. I'd be willing to contribute to such a fund for BitShares development if it existed. Basically it sounds like funders could maintain control over expenses through a system of rolling randomized juries that act as a temporary board for authorizing fund transactions. The end of the paper mentions an idea to extend bitcoin multi-signature accounts to be controlled by rolling juries/boards. Will someone do this with bitcoin and beat us to the punch? Is there anyone else that thinks BitShares could benefit by implementing such a protocol?

Yes but I figured the same problem would still apply, if workers are setting "a pay rate" as a % and they are all maxing it out at 100%. I read the link but there are ambiguities on how this could be implemented. Can you give a brief summarize from your perspective?

Really really important feature I hope the next version has this.