TTD (the WinDbg one) works very well for complex multithreaded apps. (The caveat being the performance hit you get from emulation). It's one of the big advantages it has over rr.
The main use case I saw for TTD was debugging complex memory corruption issues. Certain types of issues like stack corruption became trivial to debug under TTD. It was also very useful for capturing a repro. If a customer complained about something and I couldn't immediately reproduce it or get a crash dump, I'd ask them to record a TTD trace. More than 75% of the time I'd say it was enough to root cause the bug, without spending tons of time figuring out the repro steps.
The main use case I saw for TTD was debugging complex memory corruption issues. Certain types of issues like stack corruption became trivial to debug under TTD. It was also very useful for capturing a repro. If a customer complained about something and I couldn't immediately reproduce it or get a crash dump, I'd ask them to record a TTD trace. More than 75% of the time I'd say it was enough to root cause the bug, without spending tons of time figuring out the repro steps.