You don't lose anything (assuming your whole team uses the same bouncer, which is a good solution, IMO), logs will remain saved on the disk drive, but people will be unable to connect. Personally I have a bouncer running on a VPS since 2008 with 100% uptime so far, costs me $3/month and is used by 10 people.
If my bouncer goes down, I don't have the history for the period for which it was down. Congrats on 100% uptime, but that's not the numbers one should plan by.
If the bouncer goes down and your team uses only the bouncer, someone fixes the problem before new history is made, and nothing is lost. Fixing the problem means rebooting the machine, there is absolutely nothing that can go wrong with a simple IRC bouncer.
