Is it derogatory to call user a punter?

Question

I've been wondering whether it is somewhat derogatory to call a user a punter. For instance,

We should encourage punters to participate in the discussions.

Update: My apologies — I owe you an explanation. I do a lot of User Experience work for an organisation (online service) where internally users are occasionally referred to as punters. Because personas, customers and users are centric to my line of work, it bothers me every time I hear a word that may even remotely indicate users' inferiority. You know what they say — "Great UX is cultural". I've read a few references, but because English isn't my first language I wanted to find out whether there is a subtle nuance beyond a dictionary definition.

Answer 1

http://oxforddictionaries.com/definition/english/punter

noun
1 informal, chiefly British a person who gambles, places a bet, or makes a risky investment.
• a customer or client, especially a member of an audience.
• a prostitute’s client.

It certainly could be derogatory. It does indicate an off-hand or casual attitude to customer service to call consumers punters.