I do have SOME experience with this. As both of the cats that now live at my parents house (because they stayed once for a month each...and my mother proclaimed "you'd break your daddy's hear if you take them!") Anyhow, both the cats at my parents house are declawed...and my cat Dylan who is easily twice their size has all of his claws. (and quite a few pounds on each of them to boot)
He has at one point or another lived with each of these two cats individually...and each year at christmas visits them for two weeks as well.
I will say, that while Jasmine, the smallest of the three, and the only female...lived with Dylan...they used to fight A LOT and they were very brutal slap fests. They often walked past one another and pretended as if they were going to keep going...but as soon as they got up to each other bashed eachothers faces in with paw swats.
But, RARELY did Dylan ever bring his claws out. In fact I don't really think he ever did to either of the two declawed cats.
In fact Winston, the declawed male is most definitely the Alpha cat of the group. (he is a farely large Maine Coon--almost as big as Dylan)
I only worry about your situation because you have 6 cats with claws and would potentially be bringing 1 declawed into that scenario...that might be a very different situation.
I will say this much though...neighther of my two declawed kitties realize that they are...they still use a scratching post, and swat at the dogs at my parents house as if they are intending to inflict some damage!
So, if you did bring a declawed kitty in, he/she may well do just fine depending on age and attitude!
Good luck and do let me know what you decide, I would be very curious to hear how it all works out.