I don't think it's necessarily a question of size. It's just that you can only trust your own relays.
The Android relay I run on my localhost is more trustworthy than one run by someone else, on their machine, regardless of who they are, because I can see the entirety of it and verify everything.
I just setup Citrine on my phone and it's running really good. Do you know if there are other relay apps for Android, or is Citrine pretty much it for now?
I think that's the only one, so far.
That's OK. Setting it up and getting it running was a snap. I wish it had more configuration options, but it's pretty great for a personal relay that runs on your phone.