Differences between Visio Plan 1 and Visio Plan 2

Hi -- we (local government) need to make sure we don't overbuy on our new Visio licenses.  

Plan 2 has over 250,000 shapes and is downloadable

Plan 1 is online but doesn't tell you anything about how many shapes it has.

We need it for IT drawings, as well as Marking Exits and such in Fire, as well as other things.  

We are perfectly fine with online, but is Plan 1 robust enough?

The price difference is staggering when you have as many licenses as we will need.