Gig-E taps?

[InfoSec]

Has anyone had any success with gigabit "Taps"?  I'm getting a lot of blow
back that I'm hogging up the spans on all our 6500 series Cisco's and I have
not seen a gig tap work yet.  I have many 100 full duplex taps working and
would love to find a good gig tap.  I have some blackice gig sentries and
some RS 7.0 gig sentries...either way I'd rather tap..any ideas?
 
thanks,
Erin