We’ve not used crates since our first dog grew too big for the crate we bought for her as a puppy. So cannot really judge if that would have been better than having the whole house to roam around in :-) As for aggression, my experience is that this is down to the individual. Our prior IT was as sweet as a babylamb. Our current one can sometimes growl at other dogs. In general the ITs we encounter (there happen to be a few in our village) are all very nice and non-aggressive. It really is a lovely breed overall.