OK my 2 cents....
I have gone to several Garden Railroad conventions and hope to do 2019 in Portland.
And I have done the NG convention in Augusta, Maine and greatly enjoyed it.
I had planned generally to do both in future years, and am totally dismayed that they fall in the same week in 2019!
I saw many gage 1 friends at the NG Maine event, since 1:20.3 is very popular, and while is it obviously all scales, between the live steam layout and display layouts I had plenty of G, and greatly enjoyed the high level of modeling displayed everywhere.
That said, I would likely choose the GRR convention, but dang it would have been nice if this had not happened.