I've got my 881 3g connection working. It's not the fastest connection but, I think it will work fo people who have no DSL or no cable service or as a backup. Pings from the remote office to the remote user PC average around 180 ms. Does that seem right? I was able to make phone calls and video calls to the Main Branch with a little latency with the video. Also had a WebEx going at the sametime.
I', using a Cisco antenna but, Is there anything else I can do to optimize the connection?
in my personal case I have seen an increase from 45 ms (DSL+wirelessLAN) to 101 ms (3G)in latency pinging a public ip address when I have tested it.
So in your case actually it looks like a little high I agree on this.
I have given my first answer without looking at the test results.
Note: I'm located in Europe so in my case 3G type is UMTS.
Hope to help