Since Mark Hammer mentioned that every Flanger can be converted to a TZF I thought I'll give theTZF Mistress a try.

And I must say, it really sounds cool

Turning it back to normal Mistress gives you the strong feeling something is missing.
The clock trim pot is set to a fixed delay of about 4 ms. This way the TZF point is about in the middle of the LFO travel. Don't know whether the Mistress is the ideal Flanger to be converted to TZF but it's definitely worth a try.
One tiny drawback: there is a bit of "pseudo" clock" noise. It's not really problematic but I would like to know it's source. The weird thing is: the frequency of the "clock noise" (at least I initially thought it was clock noise) doesn't correspond to LFO. It sounds like it's frequency is modulated but this modulation simply is completely different from the LFO "travel". Also interesting: this "pseudo" clock noise increases if nothing is connected to the input and with the input gnded noise it is gone. This noise hasn't got anything to do with the TZF board since it is also present if the TZF board is not connected to the main board. The level is just really low. Therefore I didn't realise so far that it's there.
In addition there is a bit of hiss once the TZF board is connected to the main board. Again, nothing dramatic but I don't know where it is derived from. The hiss is also present if the input is grounded, btw.
Do you think that one reason for these noises could be that the two boards are wired together with about 10 alligator wires and the whole mess isn't boxed yet??
Below the schems.

The fixed delay:

I know there are some things that could be simplyfied, but hey... it works

E.g. the two boards both have their own PS filtering caps + Vref opamp (I just thought that having it this way might help to prevent noise). R12 (10R) is replaced by a jumper. Also C15 (15n) is not present.
Comments are highly appreciated. BTW, in case some one is interested I will try to put together a project file within the next days.
Regards,
Markus