It all depends on how much indexing (and the number of search queries) you
have to process vs. how many users you have retrieving documents and doing
actual checkin/checkout/publish activities.

Assuming you have a non-trivial amount of indexing to do and a moderate
number of users doing a moderate number of cin/cout/pub, use the higher-end
server for indexing and search - but I'm really sticking my neck out in
terms of assumptions (if so, you'll at least get a lot of feedback to help
you out).