As far as my reading of the subject goes, five isn't an issue as long as there's a good economy going. In terms of lots of compels to make up for uses of FPs for invokes and such. Ten points gives a little too much of a cushion and incentive to deny compels, which can choke things up.Question. (Hi! I'm the GM!)
We're limiting Aspects to five in order to focus the characters. FATE uses your number of Aspects in a couple of places, notably to determine starting Fate (or Force in our case) points. 5 Force points seems a little low, and I want to encourage the tagging process, so I'm considering leaving them at ten and only reducing the number of Aspects. Does that fly?
While I'm on the subject - is that your maximum number of Fate points, or can it go over?
I don't think there is a maximum they go to - you can keep storing them up if you can manage to not spend them. Your number of Aspects is simply the refresh you get at the end of every session (though if you've got more, they don't need to refresh, and you don't lose the surplus, as far as I understand). They're just the minimum you start a session with. In some of the later rules your number of Stunts take away from this refresh number, but I don't think it would apply very well here.
Something else I was thinking about - how about one or two "campaign Aspects" and/or "story arc Aspects"? If you want to push the refresh up to 10, five of those could work well. There might be a general one like "Wanted by the Empire" everyone can use, perhaps one or two related to our individual stories right now, and maybe a Destiny one for everyone too.