PCIe level performance allows super small ASIO buffer sizes (as low as 16-samples with some hardware).
That's the only real advantage to Thunderbolt (if all conditions are met).
All the talk about bandwidth is meaningless... unless you're running a large commercial facility and working at high sample-rates. 24 channels of I/O isn't near saturating the bandwidth of USB-2.
The UA Apollo Thunderbolt series is nice (average noise-floor is about -116dB).
However, the lowest ASIO buffer size is 32-samples... and yields round-trip latency right about equal to the RME Fireface UFX at a 48-sample ASIO buffer size.
If you decide to go Thunderbolt, you've got to read all the fine print.
Otherwise, you may be disappointed... or (worse) have a non-functional combination.