Oh, yeah, I think once you're over 35lb, you need a pack with genuine, structural stability and the capacity to keep the weight on your suspension system, rather than your spine. I've been in your situation many times, and still will be in the future (at least in terms of weight), and I also use a Kelty. My Kelty's a bit older, but I'm cheap...
Now, I would suggest this: spend time and effort to lighten your components, carried gear and to take a very keen eye to the project. That's what brought me here: my mega load and the load of youths I need to keep truly light. You WILL find ways and "locations" in your gear list if you read in the "Multiple Use Gear" forum, this Gear forum and the General Backpacking forum, and this won't necessarily mean you have to spend a mint or reduce your sleeping pads to 3mm vapor lace (or whatever the masochists have come up with lately).
Someone above said something to the effect that, once you're over 40 lb, what's a few more? Ha Ha, well, the answer is, "what it is, is WAY more". Do not take that attitude, at the peril of your back, your fun and your enjoyment. Remember, if you lighten your systems now, they'll only get lighter as the kids grow (in your case, several years) and start to carry a portion of what you have in the pack, now.
Ironically, it's the opposite: if you're only carrying 20lb, another ounce for a better knife or stove is freaking nothing other than digits on a spreadsheet.
Somebody else mentioned 70 pounds above! Aside from mirth at the prospect of how many particular readers here undoubtedly shrieked in horror at even the sight of such a number, I recoiled in the pain of "little brotherhood": I've carried 60 --far, far less than 70-- many times and it just plain sucks. Sure, I remember the 1970's and 1980's machismo of "heavier back, further back" and I still marvel at a dude we used to meet deep in the Sespe with a 10" cast iron skillet we'd cook bacon on, but times change and frankly, that was dumb then, too. Dear 70lb packer: you owe it to yourself to shave weight and you easily can -- my full 60 rig is down to 49 and I've added a second bear canister. Of course, I'm also working hard to avoid needing the 49 and will be much happier with 45... 70? Crazy Train.