It's been a while so I thought I would update as I 'dealt' with this the night after posting.
The Datacenter (DC) manually configures their switch ports to 10baset full-duplex. Most of their customers that only need that amount of bandwidth put a managed switch in their rack, configure for the same, and off they go.
My NAS couldn't deal with this, and apparently neither could the SG-1000. 
The other option from the DC is get a 10Mb link that's "burstable" to 100Mb.  Basically the switch port is set to 100Mb and anything you use over 10Mbps is billable and measured at the 95th percentile.
Set up that way the SG-1000 get's a full-duplex 100Mb link no problem.  So then I just set up traffic shaper with limiters on both the SG-1000 and the pfSense box on the source end to limit the traffic so that cumulatively the DC connection will never use more than 10Mbps.  We're a month in and there are no overages and the backups are working perfectly.

@pfBasic:

I think that if you go to status monitoring, select your CPU for 8 hours @ 1 minute intervals, then deselect the interrupts and processes on the graph it will give you a better idea as to what's going on.
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Basically, I think that staring at a live update feed of top is a waste of your time (in this case). That information is already summarized and visualized for you in the RRD graphs

Well that does make sense. Sounds like I'm over-complicating things by looking at the Top averages instead of utilizing the RRD graphs. Perhaps I should just use the Top info when diagnosing an issue (if any!).

Thanks for the clarification!

Thx for you answer, so i see that it works on your side. Were you using UDP Packets… My PFSense as only one rule (Any-Any) and is a NAT with some port forwarding... Do you think that could be the problem ?

Gw

this is really cool.  thanks.

(too bad I no longer run a Mac.)