A Genos is a great keyboard (Just not my cup of tea) with loads of sounds and easy play features to keep users going for ages, however it sucks when it comes to in depth use, editing and adding additional voices etc.

A Montage (Or any Synth/Workstation) gives fantastic sounds, in-depth editing and a boat load of new sounds, however you have to put the work in as there are no easy play features to get you going, or if you just want to sit down and play a tune on the fly.

To solve this problem is easy, just get a Genos and a Montage (Or any other combinations) and you will have the best of both worlds, but it is expensive and each will have features you don’t need.

Enter Software, you want fantastic sounds and in depth editing for your Genos etc. then get a computer (A decent one is not that expensive these days) add some VSTs and you have a sound quality and flexibility a fraction of the price of adding a Montage (Or other Synth/Workstation) and also less bulk.
The same applies to the Montage (Or other synth/Workstation) in that you can add a computer and run a program like vArranger (Or any of the other arranger software out there) to give you all the easy play features of the Genos, for a fraction of the price with less bulk.

Would you need VSTs if you had a Montage? (Or other synth/Workstation) probably not, likewise if you had a Genos would you need vArranger? (Or other software arranger) probably not, as in both cases you are duplicating what you already have.

All of them have their place, (There is no one size fits all) so just get the combination that suits your circumstances and stop trying to make out that there is one keyboard that can do it all, as that is just complete nonsense. (Just like an Acoustic Guitar cannot do what an Electric Guitar can do, and vice versa)

A good example of how adding a computer (In this case built into the instrument) can expand the users horizons can be found here

Bill