Basically at the backend this is pure GraphQL. For Relay we need to have some Relay specific stuffs. That requires, more time.

In the client side too, we had to work a bit more.

That's why we go with Lokka[0]. It's just a client for any GraphQL backend. It has a simple cache.

It also supports Relay like declarative data fetching. Basically, you could build a complete app with it using Meteor's other tools like FlowRouter.

As a downside, you may need to fetch more data from the server.

As a benefit, you don't need to learn much to build a app. May be can reduce the code compared with Relay. (But that's subjective)

[0] - https://github.com/kadirahq/lokka