if you going on working with Nemesys Sampler, GigaStudio is the next step. GigaStudio is much more professional. You got a very detailed information of your Computer performance. You can rout all the Midi Controller to virtual sliders. That\'s really great. The 2.0 Editor has not much more features, but it is more comfortable.
If You only use the Gigapiano with Your GigaSampler than I think GigaSampler is fine enough.
My opinon is, the quality of the GigaStudio reverb and the sblive have the same range, but you can controll all effect details with Midi-Controller. That\'s a real advantage.