You've got some wierd loads there - 12 gr of Unique, and then less of two slower powders. I'd go no more than 10 grs of Unique, 11 of Herco and 12-13 of Blue Dot and be at the same velocity (but at lower pressures).
I don't use fillers - ever, and I am sure you don't need a filler with Unique (with 30/30 and with any other cartidge). I can't speak from personal experience on the other two, but they likely will do fine without a filler (in 30/30) as well. I will be so bold as to suggest that no powder needs a filler in a case the size of 30/30, as I have seen many loads with many powder and none prescribed a filler (but that assumes that there is enough powder to kick the velocity up to the 1700+ fps range with the slower powders). With larger cases you do find powders that will not ignite reliably without a filler (e.g. 45/70), and I just avoid those powders.
If I could choose only one powder for all my handguns and rifles, it'd be Unique. That having been said, it's not my powder of choice for anything I can think of, but no other powder does as well across so many cartridges. People just don't sing its praises because it's old (i.e. not new) and supposedly "dirty".