Are all fuses created equal?

I blew all the rail fuses in my RB-1080 amp, but didn't know it. Put it into the shop, ListenUp in Denver, and they treated me right. Told me what was wrong, replaced the blown fuses and tighten everything up, tested it out, etc. I brought it home and it ran fine for about 3 months, then the rail fuses blew again. I replaced them with slow-blow fuses and have not experienced a blow-out since. That was 2 years ago. The RB-1080 blowing rail fuses is a known issue.
Some A'gon'rs have posted that replacing fast-blow fuses with slow-blow is risky for your speakers, because the amp is allowed to pump more current into them before the fuses blow, but I haven't had any problems.

I'm not an electrical engineer, the are much smarter people on this forum than I, but it seems to me that replacing a slo-blow with a fast blo fuse presents less of a risk than vice versa. The fast blo fuse should fail faster than a slo-blo, which would mean less risk of voltage spikes throughout the remainder of the circuit.
I would definitely try to obtain fuses with identical markings tho. I just went to rat-shack and the guy there selected the slow-blows for me, i brought my blown fuse with me and told him I wanted a slow-blow version. I also scoured the internet and found a list of approved fuses deep in the innards of the Rotel site. it was a spreadsheet of fuse types per amp.