@Giffro
Technically your flat top pickups are passive,same as the ones in my 2nd gen TL-5. VFLs are active in that they need battery power to work,dead battery with VFLs means no sound. I think the change from flat top to radius for Peavey pickups was twofold.To save money and strengthen the Peavey brand. There's no end of basses with flat top pickups,not so many with radius ones. If most of your parts are standard sized across the product range there's no need to re-set machines. Both 4 and 5 string VFL loaded basses use the same pickup,that'll be the "wide aperture" part of the VFL blurb.