The Apollo Twin is Thunderbolt only (no Firewire) and it doesn't have Windows drivers.
There is a new Apollo Twin USB unit... and it does have Windows drivers (no Mac drivers).
FWIW, Windows doesn't have "PCIe via Thunderbolt" drivers for Thunderbolt 2.
Thunderbolt 3 (via USB-C connection) is supported with the latest Z170x motherboards and Windows 10 (with full PCIe via Thunderbolt drivers). Problem is... there are currently no Thunderbolt 3 peripherals.
Thunderbolt provides access to the PCIe bus (nothing more... nothing less).
Yes, it has significantly more bandwidth than USB2.
But... most audio interfaces are nowhere near saturating the USB2 bus.
Thus, throwing more bandwidth at the situation doesn't improve performance.
ie: If your car's top speed is 100mph, it doesn't matter if you're on a two lane highway... or an 8-lane freeway.
The car's max speed is still 100mph.
If you've not priced some Thunderbolt peripherals, you may be shocked.
ie: An external Thunderbolt 1 drive enclosure is ~$300 (room for 2 or 3 drives - includes no drives).
A prepackaged 1TB Thunderbolt HD is ~$200.