I think you'll be very disappointed with both. Best to send them to me for a proper disposal.
The NS is a very arcy ball by nature. Not quite as rolly as the sequel, but still. With your hand, you will probably find it handles all the oil you could want. It may be too strong, in which case I encourage you to send it to me for a proper disposal.
The BB is a little more angular. I wouldn't call either "skid-flip" by any stretch. It should handle medium-heavy quite well. Both come with a sheen finish and you may find you need to drill them weak or shine them up a little to keep them from burning up.
If you're using a Messenger effectively for medium-heavy, you should be real careful how strong you drill them. Longer pin-to-PAP distances, 5" or more maybe, should make them more usable.
Really, though, just send them to me.
SH