Yo Poo Poo Be Doo:
I have the DX7 synth -- yeah, I know it's an old one -- but it has so many possibilities.
Thus, I don't do midi; I record direct from the synth into my SIAB, 2816. But, with this one really built well synth, I have such a choice of sounds, plus the ability to tweak them, change them, etc.
I also use an 88 note stage piano by Korg -- it's a nice addition and has some good features and a great piano patch.
Depends on your tastes and likes and wallet. I don't use a PC program to record; but, as mentioned before, the 2816 is really a miniature PC in a box with a small screen and no mouse; however, a mouse can be used with the 4416. I'm not that much in a hurry when I'm recording anyways.
You don't need to get a DX7; however, you can take a long look at some workstations out there that have immense sounds and patches and tweaking, etc.
Depends on your goals and tastes and savvy.
Green Hornet