Sometimes, I feel a little sad when I look at my Kurzweil rack unit and remember how little it gets used nowadays. But don't unload that hardware synth just yet, Dan. It's still your best solution for zero-latency playing.
As much as I love Omnisphere, Kontakt and Zebra, I never play them in real time. Instead, I find a similar patch on one of my hardware synths and that's what I hear while recording MIDI. Not only is there no latency, there's also no CPU, memory or disk usage. That Roland module will never crash your DAW and never refuse to work because it thinks your license is invalid. It'll be compatible with every version of Windows and the C++ runtime library, no matter what Microsoft throws at you in the coming years. Best of all, it will never expect any more money from you.