On December 8, we played with five Virulent Strain epidemics with Medic, Operations Expert, Epidemiologist, and Scientist.
We kept the board under control for the whole game, but assembling cards was hard. We ended up counting cards near the end and concluding that we had six turns left to play. We then had to think for several minutes about how to get cards into the proper hands. We ended up passing two cards to the Medic and four cards to the Epidemiologist to get our cure on the last possible turn. We could not have done this without our house rule buffs for the Epidemiologist - but making it possible to win on the last turn doesn't mean that our buffs have trivialized the game.
Our house rule about choosing who takes the first turn magnifies an effect: Since the Virulent Strain is determined by which color has the most cubes at the first Epidemic, it's usually not the color with the most cards in the discard pile. The reason: the most-in-the-discard-pile color looks like an immediate threat, and so gets immediate attention, so the Virulent Strain is likely to be one of the colors that didn't get immediate attention.