Hey Punkyskunky ! Glad to hear you've been using and liking FLC. Regarding your question whether it'd be better using a more transparent preamp with the impulses, I think that it's really up to you. I don't think the Chandler would ''over-colour'' the sound. When I made the IR's, I used ''CAPI VP28'' preamps (known for their API-like roundness and punch.) So they didn't colour the sound that much, compared to say, a neve pre.
I would recommend trying both setups and roll with what you think sounds best ! And feel free to send me some sound clips if your ever do a comparaison, that could be really fun !
Best regards,
Joel