I'm from Canada, Vancouver
Bought 3100 off Conics in Japan one month ago: fast shipping and NO duties, for some unknown reason.
Bought Socket BT card bought from Cdn company
http://www.cendirect.com/ Awesome prices, awesome service, fast shipping on everything I have bought from them.
Bought dlink 660 off ebay in US for wifi: worked instantly with no configuration.
BT and gprs works like a charm with Rogers with socket bt card. (Took me a while to get it configured, but that's because I was not paying close enough attention to what I was doing and made some stupid config mistakes.)
This is my first Zaurus and I am not familiar with the 3000, so I cannot comment on whether the 3100 is worth the extra cost.
I'm using the stock rom and I am happy with it. I have no urge, yet, to change that.
Overall though, after being a Palm'er for 8 years, this unit is sweet. Strange that it's not more popular.