Advantages of Bitcoin design over Ripple

[timeofmind]

The one that stands out for me is that bitcoin gives great incentive for those to dedicate computing power to logging/verifying transactions. What incentive is there for people to run ripple servers?... granted the ripple server code is ever released... That is what is ingenious about bitcoin... due to block being mined, there is great incentive for a lot of people to continue to keep each other in check and to compete for those blocks. How many people are going to run ripple servers? If only few people are running ripple servers... does that not leave the network vulnerable? ie. dos attack, hacked and compromised servers, etc. ruining the reliability of the ripple network.