Just wanted to suggest swapping your free £5 for a 6 month trial of a paid feature of the plus. This ,means when refer a friend with a golden ticket, that instead of getting £5 that I would be able to try something new that will benefit my finances.
This could be for referring as normal or referring people from standard to plus.
I like the idea but the value of Plus for one month is £6 so 6 months will be £36.
This is a big jump from the current £5 that they give 
Perhaps they could exchange it for 1 month free instead?
I think it could be better when Plus is a little more fleshed out.
At the moment having it for 1 month is as good for having it for 12.
I also don’t think a trial would work as it is a 12 month contract. If you got 1 month free then you could cancel and Monzo have lost out on cost of the new card etc.
You could perhaps get 1 bonus month if you’re already on Plus or exchange it for £5 cash
Good ideas guys, yeah one month sounds good. Although I would be mainly suggesting it would be of a custom feature such as 1 month of Travel Insurance free or 1 month of ATM foreign allowance etc