Autocomplete on large fields

Hey guys,

There are several different posts in relation to autocomplete so I do
apologise for creating yet another.

I've read through all the autocomplete posts on the forum and the general
consensus is not to use wildcards or a prefix filter since they are so
memory intensive and slow but instead use an edge n gram filter.

Since I'm building an autocomplete that will search approx 10 fields, 2 of
which are large description fields (hundreds of words per field and
potentially different versions for different languages) is edge n gram
still the way to go? Obviously the index size will be much larger but will
the query still be efficient if I use a max gram of 14? How will memory
usage be impacted by all this or will it be impacted at all?

Any thoughts/advice would be great.