New campaign question

[Blastin]

I'm going to be starting a new age of worms campaign and I have a problem. I have only 4 players and no one wants to play a cleric or rogue. I have a fighter, wizard, monk and favored soul.
I have only read the first 3 modules, but have read comments from others here about how tough the later modules are. I'm concerned about party survival. I don't want to tell the players what characters to play. So, I would like the opinions of other DM's that have run most of the campaign.
I'm thinking of letting them play gestalt characters. My question is: will this swing the power too far in the players favor if I allow gestalt and still try to run the modules pretty much as writen?

[Cold Steel]

To the best of my knowledge, gestalt characters WILL unbalance the game if you never used them before.
Instead have at least one of the players to have access to one of the local churches for healing and such.

[Blastin]

oops...double posted topic....sorry bout that