I don't think you have to worry. I have a 76 GB partition formatted with SFS, and I have never had problems with it. Most of my partitions is over 4 GB, so it works fine.
The guide says
o The size of a file is limited to 2 GB (AmigaDOS)
o Support for partitions larger than 4 GB or located (partially)
beyond the 4 GB barrier on your drive. There is support for the
New Style Devices (NSD) and the 64-bit trackdisk commands (TD64)
which support 64 bit access.
o Supports large partitions. The limit is about 2 TB, but it can be
more depending on the blocksize (32KB/Block -> 128 TB).
No need to worry indeed :-)
