For like 9mm? I exclusively use no lube groove coated bullets. I think there is probably an argument for lube grooved bullets, but it has nothing to do with lube and everything to do with providing a place for material displaced by the rifling. I don't know if it's worth the loss of flexibility in bullet seating depths.
If you're using traditional bullet lube, the groove is obviously necessary. If you're powder coating, you don't need a lube groove. If you're using something like Alox, either groove or grooveless is fine. Beyond that, it's time to get out the
NOE makes bullet molds specifically for powder coating and they have no grooves at all. As someone said earlier, the groove is only for traditional lube. You don't even need a groove for XLOX and it works just fine.
Thanks ever for all the help as usual. I am setting up my press this weekend and then I will start testing some loads. I have almost enough materials for 10k of 9mm. I figure since the pricing is thru the roof break out the toys box.