Having a solo 5-car set seems a little odd - it's a shame there's an odd number of sets as otherwise you could have two or three 10-car sets, but then given the reduction in capacity vs. the standard 12, whether these would be viable in peak-hour services I'm not sure. GEML diagrams come at a premium! Integration with the 360/1 fleet does seem logical though, with no corridor connection I don't imagine they'd fit with any other Desiros very well.
The 365s though, I'm not sure. It doesn't make too much sense to split them up as you'd be left with two pretty small fleets, but I really don't see the need for 40 units just to cover extra peak capacity out of Kings Cross, given the number of TL off-peak services that will cover their routes.