You see you are learning!
A few things first!
1) This projector will not do 3D. **
2) The one Sparge told you about is 200 brighter...but how much that is in real world is not that much IMO. A little brighter for more money...you make the call...you are looking for early starts!!.....but I think that would only equal minutes over the 2,800.
There is a refurb for a little less from Epson but for the difference, I would stick with the new one.
The 710 (same family as the 725 I believe) version refurb is 399 & the 707 is $299.00
** for me 3D is useless....I don't like it but I am not you.......do your kids at this age
?? It is your call. But you will get HD with a Blu-ray player.......not bad. Will you still be using this projector in five years maybe.....but again it is up to you. I feel just because it is there does not mean you need it.
Keep in mind your budget
Blow up gemmy screen is $159.00 plus tax & s/h Sparge's Screen (good value screen) $259.00
Blu-ray players $50 +
Audio system (300.00 & up)
Seats ( tell people to bring their own & have a few carpets for the kids to sit in front)
Pop Corn machine Etc ($160.00 to over $600.00)
What I have said should be seconded & viewed by at least a third person.....I don't have this projector but others do...so please wait for a few others to make sure this is all correct & take in some more ideas before buying.
Please don't rush on this....you are close