E60 Business Sat Nav update

Hi to all, A query from a Newbie(I've searched for a similar query, without success). I have a Dec 2008 520D import to Ireland from UK. Lovely car & lots of extras. I see that 2011 discs are available from a number of independents (some mentioning endorsement by this Forum) and indeed there are some links on this Forum also.
I wonder how up-to-date these discs are? I reckon that they can only be as current as the info on new roads are notified to whatever central database is used. If there is any delay in this process, then I imagine you will be disappointed and still find yourself flying through space, when driving on a new road.
In recent years, the construction downturn had resulted in fewer new road projects. So, there is less liklihood of a disc going out of date.
Has anybody had any bad experience of such an "indy" disc? Any danger of IT issues/interference with system in car, etc? Has anybody been disappointed with finding that new roads were not included, as they might have expected?
Prices of around £30 seem reasonable, if you get what you think you are paying for.
All the best,
ThosH