Originally Posted by osagedr
You will get the exact same beer but with a slightly increased risk of something infecting your batch. To each their own. Some people are religious about not letting anything foreign get into their beer. I ferment lots of batches (including every single one of my lagers) in a 10g wine fermenter with a loose fitting lid and I peek quite a bit.
Exact beer? I don't know. I'm changing 2 pretty big variables here. Fermenter geometry and keeping it open, both of which from my study have effects on yeast metabolism and the resulting beer. But who knows?