Hi Vagro
Articulation voices have been around in VSTi long before Tyros 2 came about, and the ones introduced over the last few years, make SA2 look and sound positively crude.
Quality of sound will easily leave any hardware arranger in the dust.
The main problem is control, as they were designed to be used in a studio, (VST = Virtual Studio Technology) and apart from Wersi and Lionstracs (Which can load them on-board) most hardware boards don’t allow easy arranger control.
Fortunately you can get Livestyler www.live-styler.de which gives you a full arranger for your computer, and it can also use VSTi.
However before you make a decision, pop over to www.kvraudio.com (One of the best resources for VSTi) and read up a bit, that way you will then be able to determine what you actually require? (There are also some excellent free VSTi on the site)
Hope this helps

Bill