Ummm...Last invited to join the team, carries the beer????
Not fully sure (other than the beer) but, it may be similar to wall climbing (where a 3 man team seemed easier for me than a 2 man team.)
+ side: you have one more player to share the leads, share the loads, and share the laughs (or psychological stress-all the same.)
You probably will use the same alpine rack and use the same rope system (leader on twins or doubles? and second/third can follow on separate lines-possibly simul-climbing.
- side: need more fuel, food, larger tent (although, whats the weight difference between 2-person vs 3-person shelter with advantage of extra mule to carry the load?)
What other advantages vs disadvantages are there? Hard to think as I just opened some Ficklin Old Vine Port