Relying on any system without a support contract/entity that would get such things fixed as a core system sounds like a daft idea.
You find a system that works with your setup and pay for that.
If I were to deploy something like that - first things first:
- Is there in house support from IT to support Linux based systems? No? Can they retrain, how much does it cost, what would be needed, would an external provider be able to assist until transition is done?
- How to do standard office things like mail(this one can be as easy as use google apps for business, or some other web based provider, if need in house find a system that either your team can manage with or a third party provider(open-xchange comes to mind(they offer support packages and such)), documents etc...
- Core business supporting systems - be it ERP, CRM, etc... etc... it's core to your business so you should have a support contract or at least some sort of business contact with whoever's software you are using - be it a cloud based solution, or some piece of software, if there is no business support available - don't use it. This isn't a hammer that will just work with no support.
People often forget that just because it's open source it doesn't mean it's free of costs. They are just elsewhere - software is free, and you get free support if you are willing to wait for responses from commuinty/do your own research. But if you need support on business critical things - then don't rely on that.
As someone who loves open source and software available for it even I need to look at the business case for everything I suggest to the company be it storage(go with $random server and disks or a dedicated storage system from a known storage vendor), be it servers, firewall etc...