Any educational facility considering this offer by Linden Labs had better hope that their trustees aren't aware of Open Simulator's existence!
Even with a 50% discount Second Life is horrendously expensive, and whilst there may be the 'security' of having hosting taken care of by a specialist company, this, if needs must, would be better served by an independent Open Simulator hosting company such as Zetamex or Dreamland Universe, though to my mind the actual setting up, and administration of a grid forms a valuable educational excercise in itself.
There is also the factor than Second Life has it's own perils as far as the educational sector is concerned, with seemingly little control over access to age inappropriate content, especially since the demise of the teen grid. Using Open Simulator allows educators far more control over access, and indeed the flexibility to connect to the outside metaverse, or not as the case may be.
And what about content retention? More or less anything created inside Second Life stays in Second Life as there is no mechanism to export regions or inventory and basically in practice all you put on Second Life becomes the property of Linden Labs, much like any pictures uploaded to Facebook become the property of Facebook.
Whilst even in the Open Simulator world content theft is possible, there is at least the possibility of maintaining a more complete control of what you have personally created through the use of .oar and .iar files, which already puts Open Simulator streets ahead of Second Life. It would be true to say that until relatively recently Open Simulator wasn't as technically smooth in terms of operation, (however much further ahead in terms of technical concepts and abilities) but that in itself was part of the whole Open Simulator project: it wasn't and isn't even beta software. However, as time has moved on, Open Simulator is now in many, if not most ways, not only the equal of the Linden Lab offering, but superior, (the ability to archive regions and inventory is but one case in point).
The cynic in me suspects that this apparent U turn by Linden Labs is a rather lame attempt to lure back the many hundreds, if not thousands of former educational users who have wisely fled to Open Simulator with huge benefits to both education and their pockets!