Hello.
Well, Developer will not work since that can not be used in production.
What is really boil down to is, do you need reliability or not? If that is not required, then Partner or Standard could work as long as you can run everything on one CPU.
I would think in smaller scenarios this would work fine since it is dramatically cheaper. Just make sure you know the limits. You can read more here: http://download.microsoft.com/download/e/6/f/e6fcf394-e03e-4e15-bd80-8c1c127e88e7/LicensingFAQ.doc
If you need fail over, 24/7, or more then one CPU then you need to look at Enterprise.