Nice. I've been curious to find out if my 16 was accurate or not, but had not gotten around to checking it yet.
I'm glad your's is accurate, it's always bugged me that the 14 was so far off. I took it in (twice) for warranty, and got the ever popular "could not duplicate customer concern". Then they told me I was looking at the speedometer wrong. I-kid-you-not...
I'll throw my Zumo on one of these days and confirm if my 16 is as accurate as yours is. GPS hasn't been a real priority since it's now built in...