TVC preamps: good or bad?


I was wondering what the advantages and disadvantages are of a TVC preamp? I have read elsewhere that transformers introduce coloration and aberrations in the frequency response, which is why we try to get them out of the output stage of valve amps. But ... what are the pros and cons of TVC preamps?
amfibius
Are you using the Bent TAP with your Merlin BBAM upstream or downstream of TVC? If you're having good results, I assume that the BBAM must be upstream. The BBAM's 47K input impedance and capacitive load reportedly don't mate very well with a passive.
If I understand Bobby correctly, the BBAM is almost always preferred no matter what preamp you are using.