Does the Lab Challenge make Pandemic easier or harder?
As with the original game, the more you play the In the Lab expansion, the better you get at it. When I started playing the original version with my friends, it was hard to win with 4 regular epidemics but, by the time we got the expansion pack, we were beating the game easily with 6 epidemics (or 5 virulent strain epidemics with the added mutation disease if you have the On the Brink expansion).  With the In the Lab expansion, we have almost never been able to win with 5 virulent strain epidemics and the mutation disease.  It seems like the more you add (such as virulent strain and mutation) In the Lab is harder than the regular game, but it will all depend as time goes by.