Bandwidth - Unmetered FE port or 100m commit on GE port?

[mhab12]

Our company will soon be purchasing a new port for IP transit.  The best local rates we have found (San Diego, CA) are $500 MRC for an un-metered fast Ethernet port or $400 MRC for a 100m commit on a gig-e port (billed 95% @ $4.50/mb over 100m).  My brain says take the gig-e port and limit our own traffic to 100m through pfsense or a switch, but wanted to make sure I wasn't overlooking some other glaring reason not to do it.

Thoughts/advice?

[cmb]

Take the gig port and put a limiter on it or similar.