Use ER-X to test functions for ER-8 or ER-8 Pro?

Hi,

We're thinking of buying a couple of EdgeRouters, possibly even the ER-8 or ER-8 Pro models.

Can we buy ER-X models and use them to test all the functions? Do they run the same software, with all features enabled? In particular, we make extensive use of OpenVPN to connect our various sites and want to test that this works. And of course we have the usual long lists of firewall rules.

Performance isn't something we'd be testing at this stage.

Thanks,

Colin