When I joined my team/got involved with FIRST in 2002 our team had never attended an off-season competition, and many people hadn't heard of us. We had started to make a name for ourselves by being picked by the #1 alliance at Midwest after seeding last and winning with them, but still nobody could pronounce Oconomowoc.
We went to IRI in the summer of 2002 and had a blast, we returned in 2003 and will be there in 2004 and proabably many years after. Off-season competitions are just as and even more fun, because your robot is done already, you meet tons of amazing new people/friends, travel to some different places, and you get your team out there and it starts to be recognized. If your team is active and goes to as many events as possible then people start to go, "oh yea, look out its that darn team from wisconsin" and stuff to that extent. It not only helps your team members by letting them have fun, it helps your team in the long run as well.