Thanks for pointing out GridCoin (GRC). Since this article mainly talks about XEL and GNT, I did not cover GRC.

According to this article at GRC wiki, its mechanism is premised on BOINC2, a centralized third-party service. The “miners” use the BOINC software to offer idle CPU processing power to various projects. The amount of computational contribution is then measured in a formula named the Recent Average Credit (RAC). The distribution of Gridcoins (GRC) is up to the miners' individual RAC.

The involvement of a central authority could potentially lead to a major concern of GRC network. When an attacker gains access to the centralized service, he/she can tamper The distribution of GRC arbitrarily. In addition, GRC largely relies on the existence of BOINC. If the latter experiences an outbreak, so does Gridcoin unless the Proof-of-Research (PoR) mechanism moves to a different service.

Unlike GRC, Elastic does not rely on any other third party service, or payout process on any kind of external (not tamper proof) factors. Instead, the measurement of the amount of computational contribution as well as the payout process is done entirely in the protocol itself.