RE: IK "Sonik Synth 2"-versus-CW "Demension Pro" and PJ5 "DS864" sampler
I agree with everything techead said. I have SS2, ST2XL and Dimension. These are all similar in certain ways, yet very different in other ways. I just don't think it is a matter of one being better than the other. It really depends on your preferences and needs, so it pays to do as much research as possible.
Be aware that SS2 has a lot of "raw" synth and instrument samples that require the user to tweak in order to get a more polished sound. Also, much of the focus in SS2 is toward vintage sounds. It even has a number of mellotron samples. This is in contrast with Dimension where the sounds are more consistently "polished" and "contemporary" sounding. SS2 also has "polished" and "contemporary" sounds, but if someone was expecting only "polished" and "contemporary" sounds, they might be disappointed with SS2. But if you really like vintage sounds, SS2 might be your best choice. So it all comes down to what you want.