Hi Diki
The G70 drum sets are nothing more than stripped down Fantom kits, all of which are available to buy.
You purchase Kontakt 4 or Battery 3 (Better still Komplete 6) then load in you fantom drum kits, load in your converted Roland styles, and re-map them to use the Fantom Drum Kits, Job Done.
What’s difficult in that?
Other boards at best probably have about 3 layers of drum sample, whereas VSTi have 10, 12, or more, so one of them will be close enough as to not matter, the rest of the sounds you mention are also available, so it’s just a case of loading them in, and mapping them to the appropriate notes etc. (Which with your experience would probably take about 10 -15 minutes per style)

Bill