>  Does anyone know what an upper limit might be for loading soundfiles using
> GEN01?

Limit for GEN01 is 30bit. Example:

sample rate:      44100
channels:         2
sample precision: 32 (float)

1073741823 / (44100 * 2 * 32) ~= 380.435 sec ~= 6.3 min

with double samples we have ~ 3.17 min.

tito