Hi,
The reason it works faultlessly is because all of them run quad band 2G and then the 3G is area specific because of hardware differences in the RF front end. You can run an 80,82 or 84 here, from a technical point of view, long term with no issue (regulatory is a different matter) as long as you do not mind slow speeds (except on the SL8082 as that will switch to 3G).
2G is alive and well across Europe and likely to be for 10 years or so, however, for Europe and Oz you have to be running the correct variant as 2G has effectively gone there now.
Regards
Matt