I like the look of both on metallic paint and really think you'd be happy with the results of either on metallic. I've only seen them on black in pics...they all looked good, but pics are not the same thing as seeing it in person.
TW85 found that topping UPP with Signature took most of the slickness away...interestingly he did not notice a diminished slickness with the now discontinued Paste Glaz (Signature replaced it). I have topped EX-P with Signature with outstanding results on my silver Solara.
As of yesterday, Pinnaclewax.com was offering a great deal on a Paste Glaz kit for $50 plus shipping (and the detailcity coupon code scores 15% off that).