If you can keep them, and keep up with it, I think that's wonderful!
Just to play Devil's Advocate though, I just wanted to point out a few things, because sometimes people don't realize what they're committing to. If you think these issues are not problems, then I think it's a great idea.
First, remember that they are kittens for a very short time, they are cats for a good 15 years. You will have 7 full-grown cats for a very long time, and that is a lot of work and responsibliity, and what if your situation changes?
Second, and one of the things that has always discouraged me from keeping more than one of a litter; You will have 5 kittens reaching senior status at the same time, 5 kittens who share the same genes. There's a pretty good chance that they will all start to get ill around the same time with similiar programs, and if they could very well all need a lot of extra care and expense and work, all again around the same time. It's hard enough caring for one elderly, ill cat, more than one, with a chance of dealing with 5, and then having to say goodbye all around the same time, that's more than I believe I could handle.
That's one of the reasons I've always tried to space my cats apart in years, so if I do have to care for an ill cat, its only one, and I still have younger cats to help me with the stress.
Think of having 5 to deal with.
Just some things people sometimes don't think about when keeping a whole litter, and I believe should be considered in a decision like this.
I'm not saying not to, just saying that these are some of the down sides that one needs to be aware of, so if you decide to keep them, you know the commitment you're making.