Along the same lines as the above post, my missus has a pair of sprayway all day rain pants. I was a bit dubious about their performance but a very wey day out in the Lakes a few weeks ago put any doubts to rest. They look nice but might be a tad warm for the really hot summer days.
An overtrouser consideration might the Rab Tempo trousers, made from a similar fabric to the Spark jacket
I would suggest, if you liked the Zion, to buy another Zion. I think it does look particularly smart, especially in the grey and yellow.
I own the rab neo jacket and, in my opinion, it's my go to jacket when the weather's really bad. It's kept be dry in some pretty grim weather and the large hood / chin area can really be cinched down to protect you. As with the Zion, the neoshell fabric is excellent and very breathable. The Zion would be warmer on it's own because it has a fleecy liner (I think) whereas the rab is purely a shell