We are using JIRA now in a small team (4 or 5 people) with the possibility of expanding it company-wide (which would be 200+).
With the new "starter kit" pricing I decided to evaluate Greenhopper as well. Not sure if we'll use it, but in any case, should we get the 100+ license for JIRA, we are unlikely to want to pay for everyone to use Greenhopper as well, more likely the 25-user option. Most of our users of issue tracking software are very casual, simple users and don't need bells and whistles.
Right now it looks like whatever the license for JIRA (10, 25, 50, 100, 100+), if you buy Greenhopper you have to have the same license. That seems silly, please decouple the licensing so that if most users don't need the extra features, we don't have to pay for them to sit unused.