You should first check the kind of caps that you are replacing and then to try to find the appropriate replacement. It will not produce big problems I guess but you may end with better results. Here is one useful article about replacing caps:
http://www.bext.com/replace.htm
Another top candidate are Elna caps but to be honest, Black Gates are fine choice.
Concerning the sound that you prefer - warm vs. lean - it may be that the new caps produced improvement in sound, but the improvement that you don't like. It may be that in absolute terms you have better sound now that you like less. And that is much more difficult question to answer ...
Regards
Dejan
http://www.bext.com/replace.htm
Another top candidate are Elna caps but to be honest, Black Gates are fine choice.
Concerning the sound that you prefer - warm vs. lean - it may be that the new caps produced improvement in sound, but the improvement that you don't like. It may be that in absolute terms you have better sound now that you like less. And that is much more difficult question to answer ...
Regards
Dejan