Personally I never bother with the portfolio information that my brokers hold and keep my own records of everything. If they calculate capital gains for you, they may often make assumptions that are different to what you have done. For instance if you have two lots of company A, 200 bought at $1 and 300 bought at $1.10, and then sell 100 at $1.20, unless they provide some means of you indicating to them which lot the 100 sold came from, then they might assume LIFO or FIFO, which may not be what you have done (you might have taken 50 from each lot to sell).
I just ensure that their holding quantity is correct. If they haven't updated the quantity of the particular stock that had a ticker change so that the new ticker reflects the quantity, then hopefully they should still show the quantity against the old ticker. If the ticker change was not recent (more than a few business days ago), I would query with them why they haven't updated yet. It might be a problem when you try to sell under either the new ticker (you have none to sell) or the old ticker (invalid ticker). Also, it could effect your margin requirements if you have margin.
