Implex is what McDermott and I believe Meucci used to use for their "plastic" joints. Not terribly sure what exact material composition "Implex" is made of, but I still call most "plastic" joints by the name Implex, old habit from when I started playing serious pool and learning about cues. As far as the other question, I am a VERY beginner cuemaker, and don't think I am qualified to answer much, but I will give my opinion, for what it's worth. Ivory can crack, steel can't, not sure how an ivory jointed cue shoots, but I have had a few stainless jointed cues and they seem to shoot a little stiffer than most implex/plastic/phenolic/wood-wood jointed cues I have shot with. Now, that being said, there are exceptions to all of this, I recently shot with a implex-jointed Meucci that had some custom work done on it, had a G10 ball-screw joint pin installed, and had a 314-2 shaft mated to it and it shot stiffer than any Meucci I have ever seen, it shot REALLY well (I prefer a stiff hit). You probably need to try a few different combinations to find out what YOU prefer. If I am wrong about any of this, I apologize, I am only going on what I know about.