Thanks for giving this a bump, I totally missed the question!
Midnight Sun Instant Detailer is a primarily a quick detailer with the benefits of having both ivory carnauba wax and Wet Diamond polymers in it. It is excellent at cleaning light soiling, smudges, finger prints, and bird droppings with ease. It can be used on moderately wet surfaces as a drying aid. It also imparts a considerable amount of wax/polymers on the surface which gives the paint added protection and a deeper, Midnight Sun carnauba glow.
Wet Diamond Polymer Spray is primarily a spray sealant with the benefits of being a light duty quick detail spray. Smudges and finger prints are no problem. It can be used as a drying aid as well, but only on barely wet surfaces. It has a high count of Wet Diamond polymers, so the look and slickness it leaves is very familiar. It adds more protection to the paint then Midnight Sun Carnauba with a brighter (yet still deep) Wet Diamond shine.
You can use either product over any BLACKFIRE LSP, although Midnight Sun Instant Detailer really works well over Midnight Sun Ivory Carnauba Paste (and any wax for that matter!). You can also use Midnight Sun Instant Detailer over a sealant to create that "Wet Ice over Fire" signature shine.