I have the 9-piece set and find it suits all of my needs. As for purchasing the BBM twisted, if you're going to purchase the NBNG templates (which I absolutely LOVE), try twisteds with their method, first. I find my twisteds come out perfectly with the NBNG templates (some agree with me, others like the BBM for twisteds). It's personal preference. If you don't like the NBNG method after some practice, then take the plunge and get the BBM twisted templates.
I also purchased the BBM Ultimate kit recently (just to see what it was like), but haven't opened it, yet, as there's no rush - I can make everything I need to with NBNG. HTH