I'd say no.
I've never played with just 5 players - only with 6, 7 and 8. And we're all still pretty new to the game seeing as the spies have always won and hardly any teams get rejected.
Basically, the question is if an early start is better than reduced suspicion. In most of our games the first missions have succeeded, even though some contained spies. In our later games the spies usually only won with the 4th or 5th missions, so I'd guess that with more proficient resistance players it becomes more lucrative to fail the first mission.
Five players is a difficult situation though, since there is only one other spy. I'd say that you should probably not fail the mission unless you or the other spy are directly after the second mission member. You'll want to quickly establish evidence that you are not the spy.