With the gear you plan on taking, I don't know that I would use that particular backpack. I still think its a great multi-purpose backpack, but the last two times that I went to DL while trying to travel light (which for me is just one body and two lenses), I just put my gear into my regular daypack with the lenses in their own cases like this. Made it much easier to carry extra stuff (jacket, water bottle, etc) and easier to get things in and out while on the move.
I still use the backpack you originally mentioned to store all my gear for day to day use and when I know I'll be needing to bring my whole kit.
One thing about that backpack though, I'm not that crazy with how it carries the tripod horizontal on the bottom. Mine keeps slipping off and makes it more difficult to set the pack down. My next bag will have vertical storage, but at Disney, you'll probably be better off storing it in a locker until night when you need it.

I'm buying a Kata 465 before our trip in November to replace my Canon bag and I think that pretty much says it all.
LOL and am looking around for a new one. I came across the Tenba shootout bags and kinda like them but was wondering if any of ya'll have them. If you do what are your opinions/experiences good or bad. And how much will they hold. I currently have a canon 50D, 70-300 IS USM, 28-135 USM, 50 1.8, and my newest baby the 430 EX II speedlite. And before my trip next month I am picking up the 70-200L F2.8 II and IF I get a good deal maybe the 100-400L also, so looking for something to hold at least that equipment.

My latest purchases have been Lowepro's Fastpack 200 and Slingshot 200. Both work well for my application. I find it hard to recommend a specific bag, but if you are looking at Lowepro, I would recommend a website: www.avidmaxoutfitters.com
They are a Lowepro dealer with good prices and usually throw in some type of free gift with the purchase, strap, lens bag, etc. Disclaimer:I have no association with the company, I have just used them with great success.
They also have a bag finder app that allows you to tell them what type of equipment you want to carry and they will recommend the bags.