I have a recent experience regarding trade marks which I should share.
During the summer we received an official-looking notification, complete with our logo, saying it was set to expire and it would cost X amount to continue for another ten years. This took the wind out of my sales because the figure was considerably more than I was expecting, and I spent a bit of time rooting for the original application before ringing the UK Government’s Intellectual Property Office.
It turns out the letter had been from a company, not the Patent Office. It wasn’t official. The gentleman at the Government office could not have been more helpful and I was able to renew our registration there and then over the phone in a procedure that took less than ten minutes. Cost? £1000 less than the company wanted to charge me. Mmm.
See http://www.ipo.gov.uk/t-essentialreading.pdf, which includes a warning about the above, and the whole topic of registration is clearly explained.
As for the general question of whether you should protect your distinct trade mark I think it is wise to consider it. There are checks and strict rules to be applied – see the link above – but we are glad we did it.
Bottom line is when you have something of great value then it is time and money very well spent to protect it, because we are talking about your identity, your flag, your stamp, the memorable brand defining who you are and what you do. Just don’t pay too much.