Both Decrits and Bitcoin are subject to 51% attack, but Bitcoin is not subject to this attack where a minority attacker could gain a contiguous range of TBs and disrupt the network for a period of time. In Bitcoin, the probability of the next TB being an attacker is proportional to the percent of the peers the attacker controls, thus there is never 100% contiguity of control unless attacker controls 100% of the peers.

In an orthogonal attack vector, Etlase2 claims that Bitcoin is vulnerable to disruption by DoS attacks due to the existence of mining pools, but I disputed that upthread.