I have played a lot of hardware synths and I am also familiar with some software synths and I think that we are definitely heading towards software. For instance the best electric pianos I have been able to find I have found in the Yamaha Tyros keyboard that easily beats all the Korgs and Rolands I have tried. But when I tried NI Elektrik Piano at 96KHz I was really surprised about the depth and detail of that sound, what a warm and beautiful vibe, the only thing that sucked was that you could hear some speaker distortion in the sample which made it useless. But the interesting part is that the core sound of it really was something much more than what can be found in any hardware counterparts. From that I drew the conclusion that this is only the beginning of a new era. In the future we will have more CPU power, Tera Bytes large storage devices and the memory prices will go down as it becomes mainstream. That creates ideal opportunities for software synthezisers to really shine.
Another problem that exists with hardware synthezisers is that they often lack digital connection, so that means you get addidional D/A + A/D which is complete waste of sonic quality and very inefficient. So it's not only a matter of the samples not being stored as stereo samples and detailed enough, you typically also get "mid-quality" conversion as well...
And you know, for me that run a home recording studio I also get nice conversion and amplification quality by using software synths in the digital domain. So I have already made the decision that I will be using software synths as much as possible. It's really a smart thing to do, especially in digital recording...
I know that a lot of session keyboardists have chosen the same path.
Currently you need to be extremely selective with software synthesizers, but this is the kind of landscape where technology can shine for years to come. So prepare for software...