I am someone who had a room full of hardware and slowly converted it all to VST's.
(I do still have 6 external racks though) It can be done and it sounds excellent and not only that the VST's that are coming out now are very interesting compared to the older synths and can do a lot more and sound incredible in the process.
I had several DX's and the TX816 rack which has 8 DX7's installed and that believe me sounds pretty amazing. I have got Native FM7 but it is FM8 right now. It sounds excellent and it can open and read my existing DX library which has got over 7500 sounds in it. I am happy to give anyone the library. It took me 18 months to catalogue. The VST can go into unison mode and build a sound with 8 DX patches on the one note all detuned and panned. Very fat now. You can set a higher voice count for doing massive layers playing slow evolving patches with slow attack and long release times.
If you like the standard DX sounds you will love FM8 sounds because there are more possibilities with the FM programming and the sounds are bigger and better. If you have an understanding of DX programming you won't have any problems with FM8 but even if you are not into it, there are many presets to choose from and edit. And good news, FM8 makes it easy to edit a DX sound and make more broad overall changes like filter cutoff etc even thought there is no actual filter in a DX. Very easy access to ADSR settings in both amplitude and filter areas. All essential synth parameters are on the Easy Edit page. The Easy edit concept kills the original DX programming. Took much longer to change a few things, not now though.
FM8 will take the concept further than a standard DX. Most VST equivalent plugins of your hardware synths will. I had both the DX VST and the DX hardware along side for a while and believe me FM8 sounds fantastic and exactly like the real thing. (
Sorry but I don't agree with dubdisciple above. They are exactly the same, I had no problems getting a perfect match and AB switching was very very difficult! Remember a DX is only software running around digitally and converted to an analog signal right at the end. The is no reason a computer can't do the same. With different D to A as well I find now I can get some Dx sounds to actaully sound nicer.) I have always been a DX fan and now you can continue to be if you want. My patches are amazing too. I got involved with Yamaha at one point and got the library from one of their demonstrators. Many DX sounds or patches that came out much later after the synth was born sound amazing and very lush! Even for one DX sound at a time! It is an incredible instrument.