Fuse read the whole file before try to identify it, but the identification routine uses only 64 byte from the beginning of the file to do there job. So if we try to open a big (e.g. couple of GB) not spectrum related file, we may encounter with 'some out of memory' problem... If fuse read only the first 64 byte, than it never be happen.
The other issue, if we try to open a <g|b>zipped file and it may 'explode'... (a 2G all 0 file is about 2M with gzip).