timvisee Yes and No in my opinion. For some of my Slice groups, I would prefer to not have it counted against my statistics, because the expenses there are unrelated to what I consumed myself and don't really affect me in any way (let's say when I pay a restaurant bill for my friends). For some other groups, I would like the expenses inside there to also show up in my statistics fully, because maybe it's a group with household members, and I could use the statistics to gauge if the household needs to spend less (or more) for certain things. Ideally there would be very fine-grained controls for this in the settings, but that would maybe overwhelm most people.
On the other hand, it would also be nice to be able to include payments that others have made for me and added to a Slice group. Right now, when I pay the balance later, it just shows up as one big payment and I can choose one category. That's not really helpful when the balance includes dining, shopping, and more.