Don't forget the experience distribution ratios created by the levels of your groupmates. This can have a dramatic impact on how much exp any one member gets.
For example, if I'm in a group with:
A level 60
A level 56
A level 65
A level 61
A level 63
Myself (61)
A modifcation is placed on exp distribution so that higher level characters in a group get a larger cut of it (when you think about it, it's only fair since the higher levels should theoretically be doing more work than the lower level people...Though I've definitely seen situations where this isn't the case :D ).
Thus, the level 56 character will get the least experience from any given mob, and the level 65 will get the most. This does not necessarily mean that the level 56 character's experience will appear to be moving more slowly than, say, the level 61's, since 56 is a faster level.
Therefore, it's advantageous for a grouping bard (or any class for that matter) to join a group where he/she is at least on par with the levels of the rest of the group. Of course, this isn't very helpful if the group where you're going to get a nice cut of the experience is a really sucky one in general, so once again the other factors take precedence.
Personally, my connection is hyper unstable (go go gadget 28.8k on a WinModem) so I've essentially been forced to group for my exp from level 6 onward.