Goodness this is a heated subject.
I just want to say as a mother of a child with a medical condition who needs to be in a stroller (well he's 10 now so I have to what else is available now) that it isn't always evident if an older child is in a stroller due to an unseen medical issue. If you looked at my DS you would just think he was a slighly small, skinny, 10 year old. The fact is he has a life threatning illness if hegets overly tierd can put make him more llikely to become ill. We take every precaution we can to keep him safe (since he should be able to enjoy WDW too) and one of those is a stroller.
I know that alot of posters have said that is is exceptible for a child with medical condition to be in a stroller, I just want to remind everyone that it isn't always easy to tell which child has a condition and which doesn't. I just want to bring this up since people have mentioned people giving dirty looks to someone pushing around an older child around the parks.
Last year I brought my son (who had just turned 9) to the parks in a Volo umbrella stroller. I probably got a look or two, but I must admite that I wasn't really paying attention to it. My thoughts were on the fun we were having. One woman did ask me why my son got to go in a diffrent line for ST (we had a sticker for the stroller to be used a wheelchair). She thought it was because he had on a birthday button because she wanted to get special line access because it was her DD's b-day. I had to explain that my DS had a medical condition, my son was in the wheelchair entrance, and it didn't mean we would have a lesser wait in that entrance. She still walked away from me shooting me daggers.
I guess it's true what they say about assuming.
I have read most, but not all posts, and I will say that I was under the impression that 99% of them were about children without any medical condition (seen or invisible). I believe one area that every person on this thread can agree is that children (or adults for that matter) with special needs should address them however it works best for them - especially at WDW - so that they can all have a great time.
However, on the topic of able-bodied 8 year olds in strollers...OP you are free to do what you want, but since you asked for my opinion:
1) I believe that 8 is way past the age for appropriateness in a stroller. Not that he won't get tired - adults get tired there too! But because they are way old enough to be taking responsibility for themselves (of course, not carrying them ever would be the first step toward this). In other words, if you are going to be whiney at WDW, then, for my own kids, you don't deserve to be there. And - to start learning now that you have to work for what you get is not a bad idea. So if you WANT the fun of WDW, you can't expect to just sit there like a king/queen while I do all the work for you to have that fun.
2) I personally dislike the 'entitlement' of many of the next generation. And I personally also feel that this type of situation adds to/promotes it. I have seen teenagers and young adults who have no appreciation for things they are given and instead want more or want it handed to them with no finger lifted on their own part. I know that all of you posting on this do not fall into this category as you will be commenting about how your child is not entitled and constantly appreciative, so I am not referring to you. But I'm guessing that you have seen others who fall into this category - they just likely won't post here.
3) I know that with my own whiney child constantly giving her ice cream or pizza or whatever will appease her and make it a quieter vacation overall, but I do not believe that is the best way to parent her. I feel the same about putting her in a stroller to appease her.
4) There are many posts here about 5 or 6 year olds and how they ended up in a stroller...I personally feel there is a BIG difference between 5 and 8. I might agree with you on the 5 year old.
And, to add my own personal experience. The rule in our house was no stroller at WDW after 5. When ds was 6 and dd was 5 - he walked with no issues. First trip after dd was 6 she did get tired/whiney a couple of times. But last year with them 7 and 8 they went all day long, no issues, could stay late at the parks, etc. I think part that helped dd was knowing that a stroller was not an option at all after she turned 6. She wasn't expecting it and knew it wasn't going to happen. That way she know her only option was to walk.
Good luck and enjoy your vacation.