Can you write software customizations that are specific to our organization and if yes how does that hinder our ability to upgrade to future releases?

Yes, Fitrix ERP is fully customizable at the source code level. There is no such thing as a feature that we cannot add to Fitrix for you (or you can have your programmers add features). Our first choice will be to design the feature in a way that will benefit all of our customers and add it to the product, but if you need a truly custom feature we can create it for you. Fitrix ERP has an elaborate infrastructure designed to manage custom features and segregate the custom code from the package code to allow even highly customized systems to continue to accept patches, new features, and major upgrades. As a rule of thumb, for every $1 you spend in custom features, you will probably spend $.07/year maintaining that feature including the impact on the upgrade process.