Actually that sizing guide is totally unusable for comparison to SG510.
SG510-C cannot run SGOS 6.6 at all, nor is it in any way shape or form comparable to any of the S-Model units listed in that document.
S models have one or more modern multi-core cpu's (3GHz+) where the SG510 has only 1 single core cpu that is rather old and slow.
SG510-C has also been end of life for over a year now, so it'll be hard to get any kind of sizing documents for that unit.