I guess the added inductance from the slow-blow fuses could conceivably alter the sound a bit, but I wouldn't expect it to be "weightier".

Oh well, golden fuses for golden ears I guess.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8