If it's as heavy as you say it's going to be, I'd use whatever suits your needs. Should you need to move it around once in awhile, feet should be fine. If you're sure about placement and thoughts of isolation of the rack will keep you up at night, go with the spikes. :-)
I don't use a TT so my take is probably off, at best.
All the best,
Nonoise
I don't use a TT so my take is probably off, at best.
All the best,
Nonoise