The purpose of this thread is more for documentation than for asking solutions, even though feedback is welcome 
With @enricostn we encountered a bump on our way to spree 2-0-stable.
Problem
Incompatible paper_trail version between what is used in OFN to version Enterprise fields, and the dependency introduced in spree_i18n branch 2-0-stable
Bundler could not find compatible versions for gem "paper_trail":
In snapshot (Gemfile.lock):
paper_trail (= 3.0.8)
In Gemfile:
paper_trail (~> 3.0.8)
spree_i18n was resolved to 3.1.0.beta, which depends on
globalize3 (~> 0.3.0) was resolved to 0.3.0, which depends on
paper_trail (~> 2)
Running `bundle update` will rebuild your snapshot from scratch, using only
the gems in your Gemfile, which may resolve the conflict
Option 1
Create a temporary fork of spree_18n to get rid of the model translation functionnality, and the dependency on the globalize3 gem.
This work has been done later in the project and it means a lot of modifications:
Option 2
Create a temporary fork of globalize3 and upgrade its paper_trail dependency to version ~> 3.0.8
After a quick look at the changelog I have not found a lot of breaking changes between paper_trail 2 and paper_trail 3. But this requires more investigation 
Option 2 seems more reasonable to me given this is a temporary solution. In future versions of spree_18n the internationalization of spree is well separated from the models content translations (extracted to spree_globalize gem).