Is combined primer/paint a good choice for house exterior?

[Surfing Bird]

My 100 year old clapboard sided house is in need of paint. The contractor I'm thinking of hiring wants to use a combination primer/paint product so that only one coat would be applied, rather than spot priming and then painting. Is the combination product okay to use? Thanks in advance for any advice.

[jeremymichael]

yes its a good combination to use

[Adamblake33]

Primer is good because it will look more even when done. How good does it have to look?